Document and Entity Information	12 Months Ended
Document and Entity Information	Dec. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	L3 TECHNOLOGIES, INC.
Entity Central Index Key	0001039101
Document Type	8-K
Amendment Flag	true
Amendment Description	Recast for segment realignment changes and Accounting Standards Update 2017-07
Document Period End Date	Dec. 31, 2017

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 662	$ 363
Billed receivables, net of allowances of $18 in 2017 and $13 in 2016	723	700
Contracts in process	1,933	1,858
Inventories	389	330
Prepaid Expense and Other Assets, Current	300	175
Assets held for sale	135	0
Assets of discontinued operations	306	481
Total current assets	4,448	3,907
Property, plant and equipment, net	1,110	1,107
Goodwill	6,615	6,374
Identifiable intangible assets	292	229
Other assets	264	248
Total assets	12,729	11,865
Current liabilities:
Accounts payable, trade	531	419
Accrued employment costs	493	462
Accrued expenses	217	188
Advance payments and billings in excess of costs incurred	509	476
Income taxes payable	19	22
Other current liabilities	367	392
Liabilities held for sale	17	0
Liabilities of discontinued operations	226	235
Total current liabilities	2,379	2,194
Pension and postretirement benefits	1,313	1,177
Deferred income taxes	158	189
Other liabilities	398	356
Long-term debt	3,330	3,325
Total liabilities	7,578	7,241
Commitments and contingencies (see Note 18)
Stockholders' Equity Attributable to Parent [Abstract]
Common stock: $.01 par value; 300,000,000 shares authorized, 77,876,687 shares outstanding at December 31, 2017 and 77,232,204 shares outstanding at December 31, 2016	6,519	6,285
Treasury stock (at cost), 83,362,412 shares at December 31, 2017 and 82,385,075 shares at December 31, 2016	(7,404)	(7,224)
Retained earnings	6,659	6,218
Accumulated other comprehensive loss	(691)	(726)
Total shareholders' equity	5,083	4,553
Noncontrolling interests	68	71
Total equity	5,151	4,624
Total liabilities and equity	$ 12,729	$ 11,865

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Allowances for billed receivables	$ 18	$ 13
Stockholders' Equity Attributable to Parent [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares outstanding (in shares)	77,876,687	77,232,204
Treasury stock at cost (in shares)	83,362,412	82,385,075

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net sales:
Products	$ 6,733	$ 6,453	$ 6,600
Services	2,840	2,757	2,631
Revenue, Net	9,573	9,210	9,231
Cost of sales:
Products	(5,991)	(5,817)	(6,016)
Services	(2,551)	(2,435)	(2,326)
Total cost of sales	(8,542)	(8,252)	(8,342)
Goodwill impairment charge	0	0	(46)
(Loss) gain related to business divestitures	0	0	(31)
Operating Income (Loss)	1,031	958	812
Interest expense	(169)	(164)	(162)
Interest and other income (loss), net	9	17	(10)
Debt retirement charges	0	(7)	(1)
Income from continuing operations before income taxes	871	804	639
Provision for income taxes	(102)	(171)	(132)
Income from continuing operations	769	633	507
(Loss) income from discontinued operations, net of income taxes	(76)	91	(732)
Net income (loss)	693	724	(225)
Net income from continuing operations attributable to noncontrolling interests	(16)	(14)	(15)
Net income (loss) attributable to L-3	$ 677	$ 710	$ (240)
Basic earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	$ 9.65	$ 7.99	$ 6.10
Discontinued operations (in dollars per share)	(0.97)	1.18	(9.07)
Basic earnings (loss) per share (in dollars per share)	8.68	9.17	(2.97)
Diluted earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	9.46	7.86	6.01
Discontinued operations (in dollars per share)	(0.95)	1.15	(8.94)
Diluted earnings (loss) per share (in dollars per share)	8.51	9.01	(2.93)
Cash dividends declared per common share (in dollars per share)	$ 3	$ 2.8	$ 2.6
Weighted average common shares outstanding:
Basic (in shares)	78.0	77.4	80.7
Diluted (in shares)	79.6	78.8	81.9

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Statement of Comprehensive Income [Abstract]

Net income (loss)

$ 693

$ 724

$ (225)

Other comprehensive income (loss):

Foreign currency translation adjustments

124

(77)

(120)

Unrealized gains (losses) on hedging instruments

^[1]

(3)

Pension and postretirement benefit plans:

Amortization of net loss and prior service cost previously recognized

^[2]

Net (loss) gain arising during the period

^[3]

(137)

(119)

Net change in pension and postretirement benefit plans

(92)

(89)

133

Total other comprehensive income (loss)

(152)

Comprehensive income (loss)

728

572

(215)

Comprehensive income attributable to noncontrolling interests

(16)

(14)

(15)

Comprehensive income (loss) attributable to L-3

$ 712

$ 558

$ (230)

[1]	Net of income taxes of $1 million in 2017, $5 million in 2016 and income tax benefits of $2 million in 2015.
[2]	Net of income taxes of $14 million in 2017, $18 million in 2016 and $24 million in 2015.
[3]	Net of income tax benefits of $42 million in 2017, $69 million in 2016 and income taxes of $49 million in 2015. The 2015 amount includes $9 million (net of income taxes of $5 million) for the reclassification of actuarial losses into net income related to the Marine Systems International business divestiture in accordance with Accounting Standards Codification 715, Defined Benefit Plans – Pension.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Income tax expense (benefit) on unrealized gains (losses) on hedging instruments	$ 1	$ 5	$ 2
Income tax (expense) on amortization of net loss and prior service cost previously recognized	14	18	24
Income tax expense (benefit) on net (loss) gain arising during the period	$ 42	$ 69	49
Amount includes in other comprehensive income (loss), net actuarial gain (loss), before tax			9
Other comprehensive income (loss), net actuarial gain (loss), tax			$ 5

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2014	$ 5,360	$ 1	$ 5,798	$ (6,111)	$ 6,181	$ (584)	$ 75
Beginning Balance (in shares) at Dec. 31, 2014		82.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(225)				(240)		15
Other comprehensive income (loss)	10					10
Distributions to noncontrolling interests	(16)						(16)
Cash dividends declared	(213)				(213)
Shares issued:
Employee savings plans	120		120
Employee savings plans (in shares)		1.1
Exercise of stock options	74		74
Exercise of stock options (in shares)		0.7
Employee stock purchase plan	34		34
Employee stock purchase plan (in shares)		0.3
Vesting of restricted stock and performance units (in shares)		0.7
Repurchases of common stock to satisfy tax withholding obligations	(33)		(33)
Repurchases of common stock to satisfy tax withholding obligations (in shares)		(0.3)
Stock-based compensation expense	49		49
Treasury stock purchased	(740)			(740)
Treasury stock purchased (in shares)		(6.4)
Other	9		9
Ending Balance at Dec. 31, 2015	4,429	$ 1	6,051	(6,851)	5,728	(574)	74
Ending Balance (in shares) at Dec. 31, 2015		78.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	724				710		14
Other comprehensive income (loss)	(152)					(152)
Distributions to noncontrolling interests	(17)						(17)
Cash dividends declared	(220)				(220)
Shares issued:
Employee savings plans	115		115
Employee savings plans (in shares)		0.9
Exercise of stock options	53		53
Exercise of stock options (in shares)		0.6
Employee stock purchase plan	31		31
Employee stock purchase plan (in shares)		0.4
Vesting of restricted stock and performance units (in shares)		0.5
Repurchases of common stock to satisfy tax withholding obligations	(21)		(21)
Repurchases of common stock to satisfy tax withholding obligations (in shares)		(0.3)
Stock-based compensation expense	49		49
Treasury stock purchased	(373)			(373)
Treasury stock purchased (in shares)		(3.0)
Other	6		6
Ending Balance at Dec. 31, 2016	4,624	$ 1	6,284	(7,224)	6,218	(726)	71
Ending Balance (in shares) at Dec. 31, 2016		77.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	693				677		16
Other comprehensive income (loss)	35					35
Distributions to noncontrolling interests	(19)						(19)
Cash dividends declared	(236)				(236)
Shares issued:
Employee savings plans	113		113
Employee savings plans (in shares)		0.8
Exercise of stock options	46		46
Exercise of stock options (in shares)		0.5
Employee stock purchase plan	32		32
Employee stock purchase plan (in shares)		0.2
Vesting of restricted stock and performance units (in shares)		0.3
Repurchases of common stock to satisfy tax withholding obligations	(18)		(18)
Repurchases of common stock to satisfy tax withholding obligations (in shares)		(0.1)
Stock-based compensation expense	53		53
Treasury stock purchased	(180)			(180)
Treasury stock purchased (in shares)		(1.0)
Other	8		8
Ending Balance at Dec. 31, 2017	$ 5,151	$ 1	$ 6,518	$ (7,404)	$ 6,659	$ (691)	$ 68
Ending Balance (in shares) at Dec. 31, 2017		77.9

CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 3	$ 2.8	$ 2.6

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income (loss)	$ 693	$ 724	$ (225)
Less: loss (income) from discontinued operations, net of tax	76	(91)	732
Income from continuing operations	769	633	507
Depreciation of property, plant and equipment	172	156	161
Amortization of intangibles and other assets	53	42	42
Deferred income tax (benefit) provision	(8)	27	18
Stock-based employee compensation expense	53	49	46
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP	106	102	98
Goodwill impairment charges	0	0	46
Amortization of pension and postretirement benefit plans net loss and prior service cost	59	48	67
Amortization of bond discounts and deferred debt issue costs (included in interest expense)	6	8	8
Gain on sale of property, plant and equipment	(31)	(5)	0
Loss related to business divestitures	0	0	31
Other non-cash items	9	17	(3)
Changes in operating assets and liabilities, excluding amounts from acquisitions, divestitures, and discontinued operations:
Billed receivables	(18)	1	61
Contracts in process	(70)	26	6
Inventories	(69)	22	(38)
Other assets	(13)	29	(27)
Accounts payable, trade	99	(5)	(27)
Accrued employment costs	28	10	35
Accrued expenses	32	(6)	23
Advance payments and billings in excess of costs incurred	13	(73)	(7)
Income taxes	(39)	33	(9)
Other current liabilities	(42)	(20)	3
Pension and postretirement benefits	(48)	(57)	(8)
All other operating activities	(76)	(15)	2
Net cash from operating activities from continuing operations	985	1,022	1,035
Investing activities:
Business acquisitions, net of cash acquired	(316)	(388)	(320)
Proceeds from the sale of businesses, net of closing date cash balances	18	561	318
Capital expenditures	(224)	(210)	(195)
Dispositions of property, plant and equipment	74	21	3
Other investing activities	(5)	6	4
Net cash used in investing activities from continuing operations	(453)	(10)	(190)
Financing activities:
Proceeds from sale of senior notes	0	547	0
Repurchases, redemptions and maturities of senior notes	0	(856)	(297)
Borrowings under revolving credit facility	1,328	819	1,194
Repayments of borrowings under revolving credit facility	(1,328)	(819)	(1,194)
Common stock repurchased	(180)	(373)	(740)
Dividends paid	(236)	(220)	(214)
Proceeds from exercise of stock options	46	53	48
Proceeds from employee stock purchase plan	32	31	34
Debt issue costs	0	(10)	0
Repurchases of common stock to satisfy tax withholding obligations	(18)	(21)	(33)
Other financing activities	(10)	(7)	(3)
Net cash used in financing activities from continuing operations	(366)	(856)	(1,205)
Effect of foreign currency exchange rate changes on cash and cash equivalents	20	(13)	(19)
Net cash from (used in) discontinued operations:
Operating activities	117	19	90
Investing activities	(4)	(6)	(7)
Net cash from discontinued operations	113	13	83
Change in cash balance in assets held for sale	0	0	61
Net increase (decrease) in cash and cash equivalents	299	156	(235)
Cash and cash equivalents, beginning of the year	363	207	442
Cash and cash equivalents, end of the year	$ 662	$ 363	$ 207

Description of Business	12 Months Ended
Description of Business	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	L3 Technologies, Inc. (L3 Technologies, Inc. and, together with its subsidiaries, referred to herein as L3 or the Company) is a prime contractor in Intelligence, Surveillance and Reconnaissance (ISR) systems, aircraft sustainment (including modifications and fleet management of special mission aircraft), simulation and training, night vision and image intensification equipment, and security and detection systems. L3 is also a leading provider of a broad range of communication, electronic and sensor systems used on military, homeland security and commercial platforms. The Company’s customers include the United States (U.S.) Department of Defense (DoD) and its prime contractors, U.S. Government intelligence agencies, the U.S. Department of Homeland Security (DHS), foreign governments, and domestic and foreign commercial customers. In the third quarter of 2018, the Company completed a realignment of its business segments to maximize growth and improve its integration and collaboration across the enterprise. As a result of the realignment, L3’s structure consists of the following three reportable segments: (1) ISR Systems (ISRS), (2) Communication and Networked Systems (C&NS) and (3) Electronic Systems. The consolidated financial statements have been recast for this segment structure. Financial information with respect to each of L3's segments is included in Note 21. ISRS: ISRS provides products and services for global ISR mission solutions from seabed to space and Command, Control and Communications (C³) markets, specializing in signals intelligence (SIGINT) and multi-intelligence platforms, including engineering, modernization and sustainment solutions for military and various government aircraft, ground support equipment and other platforms. These strategic and tactical products and services provide warfighters with the ability to detect, collect, identify, analyze and disseminate information from command centers, communication nodes and air defense systems for real-time situational awareness and response. Other major capabilities and mission solutions include space avionics and imaging payloads, Counter Unmanned Aircraft Systems mission solutions, cyber and electronic warfare, special mission command & control, modeling & simulation and life cycle support. ISRS sells these products and services primarily to the DoD and select foreign governments. The ISRS business areas are ISR Systems, Aircraft Systems, Airborne Sensor Systems, Space & Sensor Systems, Warrior Sensor Systems, MAS, Advanced Programs, Intelligence & Mission Systems, and Aerostructures. C&NS: C&NS provides network and communication systems, secure communications products, radio frequency (RF) components, satellite communication terminals and space, microwave and telemetry products. These products include secure data links that are used to connect a variety of space, airborne, ground and sea-based communication systems and are used in transmission, processing, recording, monitoring and dissemination functions of these communication systems. Other major capabilities include integrated maritime mission solutions, directed energy, lightweight unmanned undersea vehicles and naval power delivery on submarines and surface ships. C&NS sells these products and services primarily to the DoD and select foreign governments. The C&NS business areas are Broadband Communication Systems, Naval Power Systems, Advanced Communications, Space & Power Systems and Maritime Sensor Systems. Electronic Systems: Electronic Systems provides a broad range of products and services, including components, products, subsystems, systems and related services to military and commercial customers. These products and services serve niche markets, such as aircraft simulation and training, power and distribution, cockpit avionics, airport security and precision weapons. Electronic Systems sells these products and services primarily to the DoD and select foreign governments. The Electronic Systems business areas are Commercial Aviation Solutions, Precision Engagement Systems, Link Training & Simulation and Security & Detection Systems. On October 16, 2017, the Company’s Board of Directors approved a plan to explore strategic alternatives to sell or otherwise divest the Vertex Aerospace business. The Company expects to complete a sale in 2018. The divestiture of the Vertex Aerospace business represents a strategic shift by the Company to exit the logistics solution and maintenance services business for military aircraft where the Company does not provide complex ISR systems integration and modification. The Vertex Aerospace business generated sales of $1.4 billion in 2017, $1.3 billion in 2016 and $1.2 billion in 2015. The assets and liabilities and results of operations of the Vertex Aerospace business are reported as discontinued operations for all periods presented. On December 7, 2015, the Company entered into a definitive agreement to sell its National Security Solutions (NSS) segment to CACI International Inc. The transaction was completed on February 1, 2016. NSS provided cybersecurity solutions, high-performance computing, enterprise IT services, analytics and intelligence analysis to the DoD, U.S. Government intelligence agencies, federal civilian agencies and foreign governments. The results of operations of NSS are reported as discontinued operations for all periods presented. All references made to financial data in this Annual Report on Form 10-K are to the Company’s continuing operations, unless specifically noted. See Note 3 for additional information.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Principles of Consolidation: The accompanying financial statements comprise the consolidated financial statements of L3. The consolidated financial statements of the Company include all wholly-owned and majority-owned subsidiaries. All significant intercompany transactions are eliminated in consolidation. Investments in equity securities, joint ventures and limited liability corporations over which the Company has significant influence but does not have voting control are accounted for using the equity method. Investments over which the Company does not have significant influence are accounted for using the cost method. For the classification of contract related assets and liabilities, the Company uses the duration of the related contract or program as its operating cycle, which may be longer than one year, and classifies them as current. Certain reclassifications have been made to conform prior-year amounts to the current-year presentation.

All references made to financial data noted in the footnotes are to L3’s continuing operations unless otherwise specifically noted.

Accounting Estimates: The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (U.S. GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of sales and costs of sales during the reporting period. The most significant of these estimates and assumptions for L3 relate to contract revenue, profit and loss recognition, fair values of assets acquired and liabilities assumed in business combinations, market values for inventories reported at lower of cost or market, pension and post-retirement benefit obligations, stock-based employee compensation expense, income taxes, including the valuations of deferred tax assets, litigation reserves, useful lives and valuation of recorded amounts of long-lived assets, identifiable intangible assets and goodwill. Changes in estimates are reflected in the periods during which they become known. Actual amounts may differ from these estimates and could differ materially.

Revisions or adjustments to estimates for a contract’s revenue, estimated costs at completion and estimated profit or loss are often required as work progresses under a contract, as experience is gained, as facts and circumstances change and as new information is obtained, even though the scope of work required under the contract may not change. Revisions or adjustments may also be required if contract modifications occur. The impact of revisions in profit (loss) estimates for all types of contracts subject to percentage-of-completion (POC) accounting are recognized on a cumulative catch-up basis in the period in which the revisions are made. The revisions in contract estimates, if significant, can materially affect the Company’s results of operations and cash flows, as well as reduce the valuations of receivables and inventories, and in some cases result in liabilities to complete contracts in a loss position. Aggregate net changes in contract estimates amounted to increases of $184 million, or 18%, of consolidated operating income ($1.48 per diluted share) for the year ended December 31, 2017, increases of $149 million, or 16%, of consolidated operating income ($1.23 per diluted share) for the year ended December 31, 2016, and increases of $52 million, or 6%, of consolidated operating income ($0.45 per diluted share) for the year ended December 31, 2015.

Revenue Recognition: Substantially all of the Company’s sales are generated from written contractual (revenue) arrangements. The sales price for the Company’s revenue arrangements are either fixed-price, cost-plus or time-and-material type. Depending on the contractual scope of work, the Company utilizes either contract accounting standards or accounting standards for revenue arrangements with commercial customers to account for these contracts. Approximately 59% of the Company’s net sales in 2017 were accounted for under contract accounting standards, of which approximately 49% were fixed-price type contracts and approximately 10% were cost-plus type contracts. For contracts that are accounted for under contract accounting standards, sales and profits are recognized based on: (1) a POC method of accounting (fixed-price type contracts), (2) allowable costs incurred plus the estimated profit on those costs (cost-plus type contracts), or (3) direct labor hours expended multiplied by the contractual fixed rate per hour plus incurred costs for material (time-and-material type contracts).

Sales and profits on fixed-price type contracts that are covered by contract accounting standards are substantially recognized using POC methods of accounting. Sales and profits on fixed-price production contracts under which units are produced and delivered in a continuous or sequential process are recorded as units are delivered based on their contractual selling prices (the “units-of-delivery” method). Sales and profits on each fixed-price production contract under which units are not produced and delivered in a continuous or sequential process, or under which a relatively few number of units are produced, are recorded based on the ratio of actual cumulative costs incurred to the total estimated costs at completion of the contract, multiplied by the total estimated contract revenue, less cumulative sales recognized in prior periods (the “cost-to-cost” method). Under both POC methods of accounting, a single estimated total profit margin is used to recognize profit for each contract over its entire period of performance, which can exceed one year. Losses on contracts are recognized in the period in which they become evident. Amounts representing contract change orders or claims are included in sales only when they can be reliably estimated and their realization is reasonably assured. The impact of revisions of contract estimates, which may result from contract modifications, performance or other reasons, are recognized on a cumulative catch-up basis in the period in which the revisions are made.

Sales and profits on cost-plus type contracts that are covered by contract accounting standards are recognized as allowable costs are incurred on the contract, at an amount equal to the allowable costs plus the estimated profit on those costs. The estimated profit on a cost-plus type contract is fixed or variable based on the contractual fee arrangement types. Incentive and award fees are the primary variable fee contractual arrangement types for the Company. Incentive and award fees on cost-plus type contracts are included as an element of total estimated contract revenues and are recorded as sales when a basis exists for the reasonable prediction of performance in relation to established contractual targets and the Company is able to make reasonably dependable estimates for them.

Sales and profits on time-and-material type contracts are recognized on the basis of direct labor hours expended multiplied by the contractual fixed rate per hour, plus the actual costs of materials and other direct non-labor costs.

Sales on arrangements for (1) fixed-price type contracts that require the Company to perform services that are not related to the production of tangible assets (Fixed-Price Service Contracts) and (2) certain commercial customers are recognized in accordance with accounting standards for revenue arrangements with commercial customers. Sales for the Company’s businesses whose customers are primarily commercial business enterprises are substantially all generated from single element revenue arrangements. Sales are recognized when there is persuasive evidence of an arrangement, delivery has occurred or services have been performed, the selling price to the buyer is fixed or determinable and collectability is reasonably assured. Sales for Fixed-Price Service Contracts that do not contain measurable units of work performed are generally recognized on a straight-line basis over the contractual service period, unless evidence suggests that the revenue is earned, or obligations fulfilled, in a different manner. Sales for Fixed-Price Service Contracts that contain measurable units of work performed are generally recognized when the units of work are completed. Sales and profit on cost-plus and time-and-material type contracts within the scope of accounting standards for revenue arrangements with commercial customers are recognized in the same manner as those within the scope of contract accounting standards, except for incentive and award fees. Cost-based incentive fees are recognized when they are realizable in the amount that would be due under the contractual termination provisions as if the contract was terminated. Performance based incentive fees and award fees are recorded as sales when objective evidence exists that the fees have been earned.

For contracts with multiple deliverables, the Company applies the separation and allocation guidance under the accounting standard for revenue arrangements with multiple deliverables, unless all the deliverables are covered by contract accounting standards, in which case the Company applies the separation and allocation guidance under contract accounting standards. Revenue arrangements with multiple deliverables are evaluated to determine if the deliverables should be separated into more than one unit of accounting. The Company recognizes revenue for each unit of accounting based on the revenue recognition policies discussed above.

Sales and cost of sales in connection with contracts to provide services to the U.S. Government that contain collection risk because the contracts are incrementally funded and subject to the availability of funds appropriated, are deferred until a contract modification is obtained, indicating that adequate funds are available to the contract or task order.

Research and Development: Independent research and development (IRAD) costs sponsored by the Company and bid and proposal (B&P) costs relate to both U.S. Government contracts and those for international and commercial customers. The IRAD and B&P costs for certain of the Company’s businesses that are U.S. Government contractors are recoverable indirect contract costs that are allocated to U.S. Government contracts in accordance with U.S. Government procurement regulations, and are specifically excluded from research and development accounting standards. The Company includes the recoverable IRAD and B&P costs allocated to U.S. Government contracts in inventoried contract costs, and charges them to cost of sales when the related contract sales are recognized as revenue. Research and development costs that are not recoverable on U.S. Government contracts are accounted for in accordance with research and development accounting standards and are expensed to cost of sales as incurred.

Customer-funded research and development costs are incurred pursuant to contracts (revenue arrangements) to perform research and development activities according to customer specifications. These costs are not accounted for as research and development expenses, and are also not indirect contract costs. Instead, these costs are direct contract costs and are expensed to cost of sales when the corresponding revenue is recognized, which is generally as the research and development services are performed. Customer-funded research and development costs are substantially all incurred under cost-plus type contracts with the U.S. Government.

Product Warranties: Product warranty costs are accrued when revenue is recognized for the covered products. Product warranty expense is recognized based on the terms of the product warranty and the related estimated costs. Accrued warranty costs are reduced as product warranty costs are incurred or as warranty periods expire.

The table below presents the changes in the Company’s accrued product warranty costs.



	Year Ended December 31,
	2017			2016
	(in millions)
Accrued product warranty costs⁽¹⁾:
Balance at January 1	$	109		$	105
Acquisitions during this period	3			3
Accruals for product warranties issued during the period	52			51
Foreign currency translation adjustments	1			(1		)
Settlements made during the period	(66		)	(49		)
Balance at December 31	$	99		$	109

__________________


⁽¹⁾	Warranty obligations incurred in connection with long-term production contracts that are accounted for under the POC cost-to-cost method are included within the contract estimates at completion and are excluded from the above amounts. The balances above include both the current and non-current amounts.

Deferred Debt Issue Costs: Costs to issue debt are capitalized and deferred when incurred, and subsequently amortized to interest expense over the term of the related debt using the effective interest rate method. Deferred debt issuance costs, other than for line-of credit arrangements, are presented in the Company’s consolidated balance sheets as a direct deduction from the carrying amount of the associated debt liability. Deferred debt issue costs for line-of-credit arrangements are presented in the Company’s consolidated balance sheets in other assets.

Pension Plan and Postretirement Benefit Plan Obligations: The Company maintains multiple pension plans, both contributory and non-contributory, covering employees at certain locations. Eligibility for participation in these plans varies and benefits are generally based on the participant’s compensation and/or years of service. The Company’s funding policy is generally to contribute in accordance with cost accounting standards that affect government contractors, subject to the Internal Revenue Code and regulations thereon.

The Company also provides postretirement medical and life insurance benefits for retired employees and dependents at certain locations. Participants are eligible for these benefits when they retire from active service and meet the eligibility requirements for the Company’s pension plans. These benefits are funded primarily on a pay-as-you-go basis with the retiree generally paying a portion of the cost through contributions, deductibles and coinsurance provisions.

In accordance with accounting standards for employee pension and postretirement benefits, the Company recognizes on a plan-by-plan basis the unfunded status of its pension and postretirement benefit plans in the consolidated financial statements and measures its pension and postretirement benefit plan assets and benefit obligations at December 31.

The obligation for the Company’s pension plans and postretirement benefit plans and the related annual costs of employee benefits are calculated based on several long-term assumptions, including discount rates and expected mortality for employee benefit liabilities, and rates of return on plan assets, and expected annual rates for salary increases for employee participants in the case of pension plans, and expected annual increases in the costs of medical and other health care benefits in the case of postretirement benefit obligations. See Note 19, Pensions and Other Employee Benefits for additional information.

Stock-Based Compensation: The Company follows the fair value based method of accounting for stock-based employee compensation, which requires the Company to expense all stock-based employee compensation. Stock-based employee compensation is primarily a non-cash expense because the Company settles these obligations by issuing shares of L3 common stock instead of settling such obligations with cash payments.

Compensation expense for restricted stock unit and stock option awards is generally recognized on a straight-line basis over the requisite service period for the entire award based on the grant date fair value. All of the stock options granted to employees by the Company are non-qualified stock options under U.S. income tax regulations. Compensation expense for performance units payable in L3 common stock is based on the fair value of the units at the grant date (measurement date), adjusted each reporting period for progress towards the target award, and recognized on a straight-line basis over the requisite service period. Stock-based compensation expense is recognized net of estimated forfeitures.

Income Taxes: The Company provides for income taxes using the liability method. Deferred income tax assets and liabilities reflect tax carryforwards and the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting and income tax purposes, as determined under enacted tax laws and rates. The effect of changes in tax laws or rates is accounted for in the period of enactment. Valuation allowances for deferred tax assets are provided when it is more likely than not that the assets will not be realized, considering, when appropriate, tax planning strategies. Deferred income tax assets and liabilities are classified as noncurrent in the Company’s balance sheet.

Income tax accounting standards prescribe: (1) a minimum recognition threshold that an income tax benefit arising from an uncertain income tax position taken, or expected to be taken, on an income tax return is required to meet before being recognized in the financial statements and (2) the measurement of the income tax benefits recognized from such positions. The Company’s accounting policy is to classify uncertain income tax positions that are not expected to be resolved in one year as non-current income tax liabilities and to classify potential interest and penalties on uncertain income tax positions as elements of the provision for income taxes in its financial statements.

Cash and Cash Equivalents: Cash equivalents consist of highly liquid investments with an original maturity of three months or less at the time of purchase.

Contracts in Process: Contracts in Process include unbilled contract receivables and inventoried contract costs for which sales and profits are recognized primarily using a POC method of accounting. Unbilled Contract Receivables represent accumulated incurred costs and earned profits on contracts in process that have been recorded as sales, primarily using the cost-to-cost method, but have not been billed to customers. Inventoried Contract Costs primarily represent incurred costs on contracts using the units-of-delivery method of accounting and include direct costs and indirect costs, including overhead costs, and materials acquired for U.S. Government service contracts. As discussed in Note 4, the Company’s inventoried contract costs for U.S. Government contracts, and contracts with prime contractors or subcontractors of the U.S. Government include allocated general and administrative costs (G&A), IRAD costs and B&P costs. Contracts in Process contain amounts relating to contracts and programs with long performance cycles, a portion of which may not be realized within one year. For contracts in a loss position, the unrecoverable costs expected to be incurred in future periods are recorded in Estimated Costs in Excess of Estimated Contract Value to Complete Contracts in Process in a Loss Position, which is a component of Other Current Liabilities. Under the terms of certain revenue arrangements (contracts) with the U.S. Government, the Company is entitled to receive progress payments as costs are incurred or milestone payments as work is performed. The U.S. Government has a security interest in the Unbilled Contract Receivables and Inventoried Contract Costs to which progress payments have been applied, and such progress payments are reflected as a reduction of the related amounts. Milestone payments that have been received in excess of contract costs incurred and related estimated profits are reported on the Company’s balance sheet as Advance Payments and Billings in Excess of Costs Incurred.

The Company values its acquired contracts in process in connection with business acquisitions on the date of acquisition at contract value less the Company’s estimated costs to complete the contract and a reasonable profit allowance on the Company’s completion effort.

Inventories: Inventories, other than Inventoried Contract Costs, are stated at cost (first-in, first-out or average cost), but not in excess of realizable value. A provision for excess, obsolete or inactive inventory is recorded based upon an analysis that considers current inventory levels, historical usage patterns and future sales expectations.

Property, Plant and Equipment: Property, plant and equipment are stated at cost, less accumulated depreciation. Depreciation is computed by generally applying the straight-line method to the estimated useful lives of the related assets. Useful lives generally range from 10 to 40 years for buildings and improvements and three to 10 years for machinery, equipment, furniture and fixtures. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the improvements. When property, plant or equipment is retired or otherwise disposed of, the net book value of the asset is removed from the Company’s balance sheet and the net gain or loss is included in the determination of operating income. Property, plant and equipment acquired as part of a business acquisition is recorded at fair value.

Goodwill and Indefinite-lived Intangible Assets: The carrying value of goodwill and indefinite-lived identifiable intangible assets are not amortized, but are tested for impairment annually as of November 30 and, additionally on an interim basis, whenever events or changes in circumstances indicate that the carrying amount of these assets may not be recoverable. The accounting standards for goodwill allow for the assessment of qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. The Company did not utilize a qualitative assessment approach for the November 30, 2017 goodwill impairment test, as the Company chose instead to complete the quantitative testing process for each reporting unit. The Company has elected to early adopt Accounting Standards Update (ASU) 2017-04, Simplifying the Test for Goodwill Impairment, effective January 1, 2017, which eliminated Step 2 of the previous accounting standard which required computing an implied fair value of goodwill. The Company identifies any potential impairment by comparing the carrying value of a reporting unit to its fair value. The Company determines the fair value of its reporting units using a discounted cash flow valuation approach. If a potential impairment is identified, the Company will determine the amount of goodwill impairment by comparing the fair value of a reporting unit with its carrying amount. To the extent the carrying value of a reporting unit exceeds its fair value, a goodwill impairment charge is recognized. The annual impairment tests at November 30, 2017 and 2016 did not result in impairments to goodwill. The Company performed an interim impairment test during the quarterly period ended September 29, 2017 for the Vertex Aerospace reporting unit and as a result of a decline in its estimated fair value, the Company recorded an impairment charge of $187 million ($133 million after income taxes) in 2017. The impairment charge is included in the Vertex Aerospace results of operations which are classified as discontinued operations. The Company performed an interim impairment test in 2015 for the NSS and the Vertex Aerospace reporting units and due to a decline in their estimated fair values, the Company recorded aggregate goodwill impairment charges of $955 million ($46 million classified in continuing operations, for the retained businesses, and $909 million classified in discontinued operations). See Note 3 for additional information on the goodwill impairment charges.

Identifiable Intangible Assets: Identifiable intangible assets represent assets acquired as part of the Company’s business acquisitions and include customer contractual relationships, technology, favorable leasehold interests and trade names. The initial measurement of these intangible assets is based on their fair values. Identifiable intangible assets are: (1) tested for impairment whenever events or changes in circumstances indicate that the carrying amount of these assets may not be recoverable and (2) amortized over their estimated useful lives as the economic benefits are consumed. The Company reviews and updates its estimates of the duration of its customer contractual relationships. If the Company’s current estimates indicate that the duration of its customer contractual relationships have decreased, then the Company adjusts the amortization period for those customer contractual relationships to their remaining useful economic life.

Derivative Financial Instruments: The Company’s derivative financial instruments include foreign currency forward contracts, which are entered into for risk management purposes.

The Company’s U.S. and foreign businesses enter into contracts with customers, subcontractors or vendors that are denominated in currencies other than their functional currencies. To protect the functional currency equivalent cash flows associated with certain of these contracts, the Company enters into foreign currency forward contracts. The Company’s activities involving foreign currency forward contracts are designed to hedge the changes in the functional currency equivalent cash flows due to movements in foreign exchange rates compared to the functional currency. The foreign currencies hedged are primarily the U.S. dollar, the Canadian dollar, the Euro and the British pound. The Company manages exposure to counterparty non-performance credit risk by entering into foreign currency forward contracts only with major financial institutions that are expected to fully perform under the terms of such contracts. Foreign currency forward contracts are recorded in the Company’s balance sheets at fair value and are generally designated and accounted for as cash flow hedges in accordance with the accounting standards for derivative instruments and hedging activities. Gains and losses on designated foreign currency forward contracts that are highly effective in offsetting the corresponding change in the cash flows of the hedged transactions are recorded net of income taxes in accumulated other comprehensive income (loss) (accumulated OCI) and then recognized in income when the underlying hedged transaction affects income. Gains and losses on foreign currency forward contracts that do not meet hedge accounting criteria are recognized in income immediately.

Treasury Stock: The Company records treasury stock purchases at cost, which includes incremental direct transaction costs.

Translation of Foreign Currency and Foreign Currency Transactions: Transactions in foreign currencies are translated into the local (functional) currency of the respective business at the approximate prevailing rate at the time of the transaction. Foreign exchange transaction gains and losses in the years ended December 31, 2017, 2016 and 2015 were not material to the Company’s results of operations. The operations of the Company’s foreign subsidiaries are translated from the local (functional) currencies into U.S. dollars using weighted average rates of exchange during each reporting period. The rates of exchange at each balance sheet date are used for translating the assets and liabilities of the Company’s foreign subsidiaries. Gains or losses resulting from these translation adjustments are included in the balance sheets as a component of accumulated OCI and are only recognized in income when a foreign subsidiary is divested.

Accounting Standards Issued and Not Yet Implemented: In August 2017, the Financial Accounting Standards Board (FASB) issued ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities. The amendments in this update intend to better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedge relationships and the presentation of hedge results. The amendments in this update require an entity to present the earnings effect of the hedging instrument in the same income statement line in which the earnings effect of the hedged item is reported. Current U.S. GAAP provides for hedge accounting only for the portion of the hedge deemed to be highly effective and requires an entity to separately reflect the amount by which the hedging instrument does not offset the hedged item, which is referred to as the ineffective amount. The amendments in this update no longer require entities to separately measure and report hedge ineffectiveness. The new standard is effective for the Company for interim and annual reporting periods beginning on January 1, 2019, with early adoption permitted. For cash flow hedges existing at the date of adoption, the Company is required to apply a cumulative effect adjustment relating to the separate measurement of ineffectiveness to the opening balance of retained earnings. The amended presentation and disclosure guidance is required only prospectively. The Company will adopt ASU 2017-12 effective January 1, 2019. The Company does not expect the adoption of this standard to have a material effect on its financial position, results of operations or cash flows.

In January 2017, the FASB issued ASU 2017-01, Clarifying the Definition of a Business, with the objective of providing additional guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The amendments in this update provide new guidance to determine when an integrated set of assets and activities (collectively referred to as a “set”) is not a business. The new guidance requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. The new guidance reduces the number of transactions that need to be evaluated as a business. The new standard, as amended, will be effective for the Company prospectively for interim and annual reporting periods beginning on January 1, 2018, with early application permitted. The Company believes that the evaluation of whether transactions should be accounted for as acquisitions (or dispositions) of assets or businesses will be simplified under the new standard.

In February 2016, the FASB issued ASU 2016-02, Leases, which updates the existing guidance on accounting for leases and requires new qualitative and quantitative disclosures about the Company’s leasing activities. The new standard requires the Company to recognize lease assets and lease liabilities on the balance sheet for all leases under which the Company is the lessee, including those classified as operating leases under previous accounting guidance. The new standard allows the Company to make an accounting policy election not to recognize on the balance sheet lease assets and liabilities for leases with a term of 12 months or less. The accounting applied by a lessor is largely unchanged from previous guidance. The new standard, as amended, will be effective for the Company for interim and annual reporting periods beginning on January 1, 2019, with early adoption permitted. In the adoption year, the Company will be required to recognize and measure all leases using a modified retrospective approach, which requires the restatement of each prior reporting period presented. The Company is currently evaluating the expected impact of the adoption of this standard on its consolidated financial statements and disclosures related to leasing activities. The Company plans to adopt ASU 2016-02 effective January 1, 2019. Refer to Note 18 for information about the Company’s leases.

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, As Amended (commonly referred to as ASC 606), which will replace numerous requirements in U.S. GAAP, including industry-specific requirements, provides companies with a single revenue recognition model for recognizing revenue from contracts with customers and significantly expands the disclosure requirements for revenue arrangements. The new standard, as amended, will be effective for the Company for interim and annual reporting periods beginning on January 1, 2018. The two permitted transition methods under the new standard are the full retrospective method, in which case the standard would be applied to each prior reporting period presented, or the modified retrospective method, in which case the cumulative effect of applying the standard would be recognized at the date of initial application with disclosure of results under the new and old standards for the first year of adoption.

The Company will adopt the standard as of January 1, 2018, using the modified retrospective transition method, and has evaluated the impact of the adoption on its consolidated financial statements and related disclosures. Under the modified retrospective transition method, the Company will calculate and record the cumulative effect of adopting the new standard at January 1, 2018, in the Company’s Quarterly Report on Form 10-Q for the first quarter of 2018.

The Company has evaluated the changes from adopting this new standard on its financial reporting, disclosures and its various revenue streams. The Company will recognize revenue over time on most of its (i) contracts that are covered by current contract accounting standards and (ii) fixed-price type contracts that require it to perform services that are not related to the production of tangible assets by using cost inputs to measure progress toward the completion of its performance obligations. This method is similar to the POC cost-to-cost method currently used on the majority of the Company’s contracts covered by current contract accounting standards. Accordingly, the adoption of this standard will primarily impact certain (i) contracts currently covered by contract accounting standards that currently recognize revenue using the POC units-of-delivery method and (ii) fixed-price type contracts for services that are not related to the production of tangible assets that currently recognize revenue on a straight-line basis over the contractual service period.

Based on contracts in process at December 31, 2017, the Company expects to record, upon adoption of ASC 606, a net increase to shareholders’ equity ranging from $10 million to $20 million, which includes the acceleration of net sales ranging from $350 million to $400 million and the related cost of sales. The adjustment to retained earnings primarily relates to contracts currently accounted for under the POC units-of-delivery method, which would have been recognized under ASC 606 earlier in the performance period as costs were incurred, as opposed to when the units were delivered under ASC 605.

The Company will make certain presentation changes on its consolidated balance sheets to comply with the new standard. The components of contracts in process will be presented separately as contract assets or inventories based on the amounts of unbilled revenue or the cost of inventories, respectively. Advance payments and billings in excess of costs and deferred revenue, which is currently classified in other current liabilities, will be combined and presented as contract liabilities. The Company expects that the adoption of ASC 606 will result in a decrease in inventories and an increase in contract assets (unbilled receivables) primarily to reflect the impact of converting contracts currently applying the units-of-delivery method to the cost input method for recognizing revenue and profit. Additionally, the Company will reclassify approximately $50 million of capitalized contract fulfillment costs from inventories to other assets upon adoption of ASC 606. The Company accounts for contract fulfillment costs as a contract cost under current accounting standards, and capitalizes them to inventoried contract costs if they relate to contracts that are accounted for under the POC units of delivery method of revenue recognition. The Company expects the net impact of these adjustments will decrease its current assets and current liabilities each by approximately 2%.

Additionally, the Company has updated its accounting policies affected by this standard, redesigned its internal controls over financial reporting related to the standard, and determined the extent of the expanded disclosure requirements. The Company has substantially completed the evaluation of the impact of the accounting and disclosure changes on its business processes, controls and systems and has implemented the necessary changes to such business processes, controls and systems.

Other accounting standard updates effective for interim and annual periods beginning after December 31, 2017 are not expected to have a material impact on the Company’s financial position, results of operations or cash flows.

New Accounting Standards Implemented: Effective January 1, 2018, the Company adopted the FASB issued ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. Defined benefit pension and postretirement benefit cost (net benefit cost) comprise several components that reflect different aspects of the Company’s financial arrangements as well as the cost of benefits provided to employees. Under previous U.S. GAAP, those components were aggregated for reporting in the financial statements and presented within the operating section of the income statement or capitalized into assets (inventories) when appropriate. The amendments in this update require the Company to report the service cost component in the same line item as other compensation costs arising from services rendered by the employees during the period. The other components of net benefit cost are required to be presented separately from the service cost component and below income from operations. Plan administrative expenses, which were previously included in service cost, are presented together with expected return on plan assets, as a component of Interest and other income (expense), net. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The amendments in this update have been applied retrospectively for the presentation of the components of net benefit cost and prospectively for the capitalization of the service cost component of net benefit cost. The adoption of this standard increased operating income and decreased interest and other income (expense), net, each by $11 million for the year ended December 31, 2017, by $1 million for the year ended December 31, 2016 and by $27 million for the year ended December 31, 2015. The adoption of this standard did not impact income from continuing operations before income taxes for the years ended December 31, 2017, 2016, and 2015.

Acquisitions, Divestitures and Discontinued Operations

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Acquisitions, Divestitures and Discontinued Operations

. Acquisitions, Divestitures and Discontinued Operations

Business Acquisitions

The Company continually evaluates potential acquisitions that either strategically fit within the Company’s existing portfolio or expand the Company’s portfolio into new product lines or adjacent markets. The Company has completed a number of acquisitions that have been accounted for as business combinations and have resulted in the recognition of goodwill in the Company's financial statements. This goodwill includes the know-how of the assembled workforce, the ability of the workforce to further improve technology and product offerings, and the expected cash flows resulting from these efforts. Goodwill may also include expected synergies resulting from the complementary strategic fit these businesses bring to existing operations. The business acquisitions discussed below are included in the Company’s results of operations from their respective dates of acquisition.

2017 Business Acquisitions

Kigre, Inc. (Kigre). On December 18, 2017, the Company acquired Kigre, Inc., renamed L3 Kigre, Inc., for a purchase price of $13 million, which was financed with cash on hand. Kigre designs, manufactures, markets and distributes laser glass, filter glass and laser transmitter solutions involving rare earth elements. The goodwill recognized for this business was $9 million, which was assigned to the ISRS segment, and is not expected to be deductible for income tax purposes. The final purchase price is subject to customary adjustments for final working capital. The final purchase price allocation, which is expected to be completed in the second quarter of 2018, will be based on final appraisals and other analysis of fair values of acquired assets and liabilities. The Company does not expect that differences between the preliminary and final purchase price allocation will have a material impact on its results of operations or financial position.

Escola De Aviacao Aerocondor, S.A. (G-Air). On October 27, 2017, the Company acquired Escola De Aviacao Aerocondor, S.A., renamed G-Air, Inc., for a purchase price of $13 million, which was financed with cash on hand. G-Air is a European airplane and helicopter training academy located in Cascais, Portugal. The goodwill recognized for this business was $12 million, which was assigned to the Electronic Systems segment, and is not expected to be deductible for income tax purposes. The final purchase price allocation, which is expected to be completed in the second quarter of 2018, will be based on final appraisals and other analysis of fair values of acquired assets and liabilities. The Company does not expect that differences between the preliminary and final purchase price allocation will have a material impact on its results of operations or financial position.

Doss Aviation, Inc. (Doss Aviation). On September 12, 2017, the Company acquired Doss Aviation, Inc., which has been renamed L3 Doss Aviation, Inc. Doss Aviation is the sole provider of initial flight training for U.S. Air Force (USAF) pilots and offers curriculum coursework and flight training for both fixed-wing and unmanned aircraft pilots and weapons officers from its full-service, turnkey training facility. Doss Aviation also provides instructor pilots for rotary-wing aircraft for the U.S. Army, as well as global airfield service support activities at U.S. government bases, including aircraft and bulk refueling services and aircraft component repair and modification. The strength of Doss Aviation’s military training, combined with the Company’s existing training solutions, increases the Company’s position to support customers’ growing demand for trained international military and commercial pilots. The acquisition was financed with cash on hand. The goodwill recognized for this business was $37 million, which was assigned to the Electronic Systems segment, of which $13 million is expected to be deductible for income tax purposes. The final purchase price is subject to customary adjustments for final working capital. The final purchase price allocation, which is expected to be completed in the second quarter of 2018, will be based on final appraisals and other analysis of fair values of acquired assets and liabilities. The Company does not expect that differences between the preliminary and final purchase price allocation will have a material impact on its results of operations or financial position.

Adaptive Methods, Inc. (Adaptive Methods). On September 8, 2017, the Company acquired Adaptive Methods, Inc., renamed L3 Adaptive Methods, Inc., for a purchase price of $33 million, which was financed with cash on hand. Adaptive Methods delivers Undersea Warfare (USW) and Anti-Submarine Warfare capabilities for U.S. military customers and develops autonomy and sensor payload solutions for use by Unmanned Undersea Vehicles (UUVs). The acquisition provides the Company with an innovative UUV autonomy technology that will broaden its capabilities in the dynamic and growing undersea market. The acquisition was financed with cash on hand. The goodwill recognized for this business was $28 million, which was assigned to the ISRS segment, all of which is expected to be deductible for income tax purposes. The final purchase price is subject to customary adjustments for final working capital. The final purchase price allocation, which is expected to be completed in the second quarter of 2018, will be based on final appraisals and other analysis of fair values of acquired assets and liabilities. The Company does not expect that differences between the preliminary and final purchase price allocation will have a material impact on its results of operations or financial position.

Open Water Power, Inc. (Open Water Power). On May 19, 2017, the Company acquired Open Water Power, Inc., which has been renamed L3 Open Water Power, Inc. Open Water Power develops safe and high-energy-density undersea power generation technologies for use by UUVs and other maritime platforms. The acquisition enhances the Company’s growing portfolio of innovative undersea capabilities. The acquisition was financed with cash on hand. The purchase price is subject to additional contingent consideration not to exceed $17 million and is based on Open Water Power’s post-acquisition milestone achievements for the four-year period ending December 31, 2021. The Company recorded a $14 million liability on the acquisition date for the fair value of the contingent consideration. The goodwill recognized for this business was $25 million, which was assigned to the C&NS segment, and is not expected to be deductible for income tax purposes. The Company also recognized indefinite-lived intangible assets of $65 million for in-process research and development (IPR&D) costs. The purchase price and purchase price allocation of Open Water Power was finalized as of December 31, 2017, with no significant changes to preliminary amounts.

OceanServer Technology, Inc. (OceanServer). On March 17, 2017, the Company acquired OceanServer Technology, Inc., which has been renamed L3 OceanServer, Inc. OceanServer develops and manufactures autonomous, lightweight UUVs. OceanServer provides highly capable UUVs to a wide array of military, commercial and international customers. The acquisition was financed with cash on hand. The goodwill recognized for this business was $19 million, which was assigned to the C&NS segment, all of which is expected to be deductible for income tax purposes. The purchase price and purchase price allocation of OceanServer was finalized as of September 29, 2017, with no significant changes to preliminary amounts.

Explosive Trace Detection business of Implant Sciences. On October 10, 2016, the Company entered into an asset purchase agreement (APA) to acquire the explosive trace detection (ETD) business of Implant Sciences Corporation (Implant), at which time Implant entered into Chapter 11 bankruptcy protection of the U.S. Bankruptcy Code. In December 2016, Implant received U.S. Bankruptcy Court approval to consummate the APA. The ETD business bolsters the Company’s leadership in efficient, scalable security solutions and greatly enhances its capabilities in the global aviation security and national security markets. On January 5, 2017, the Company completed the acquisition of the ETD business for a purchase price of $118 million, in addition to the assumption of specified liabilities, which was financed with cash on hand. The goodwill recognized for this business was $80 million, which was assigned to the Electronic Systems segment, all of which is expected to be deductible for income tax purposes. The purchase price and purchase price allocation of the ETD business was finalized as of December 31, 2017, with no significant changes to preliminary amounts.

Net sales and income before income taxes for Kigre, G-Air, Doss Aviation, Adaptive Methods, Open Water Power, OceanServer and the ETD business, included in L3’s consolidated statement of operations for the year ended December 31, 2017, are presented in the table below.



	Year Ended December 31, 2017
	(in millions)
Net sales	$	80
Loss before income taxes	$	(1	)

2016 Business Acquisitions

MacDonald Humfrey (Automation) Limited. On November 22, 2016, the Company acquired MacDonald Humfrey (Automation) Limited, which has been renamed L3 MacDonald Humfrey (MacH), for a purchase price of £263 million (approximately $327 million). The purchase price is subject to additional, contingent consideration not to exceed £30 million (approximately $38 million) and is based on MacH’s post-acquisition financial performance for the three-year period ending December 31, 2019. The Company recorded a £21 million (approximately $26 million) liability on the acquisition date for the fair value of the contingent consideration. The acquisition was funded from cash on hand and revolving credit borrowings that were repaid before the end of 2016. The purchase price and purchase price allocation of MacH was finalized as of December 31, 2017, with no significant changes to preliminary amounts. MacH is a globally recognized leader in the deployment of operationally effective and efficient aviation checkpoint security solutions, as well as in the development of state-of-the-art process automation and collaborative robotic capabilities supporting aviation and other adjacent markets. The goodwill recognized for this business was £204 million (approximately $255 million), which was assigned to the Electronics Systems reportable segment, and is not expected to be deductible for income tax purposes. The Company also recognized identifiable intangible assets of £45 million (approximately $56 million) in the aggregate, which consisted of £6 million (approximately $8 million) for trade name, £10 million (approximately $12 million) for technology and £29 million (approximately $36 million) for customer relationships. Identifiable intangible assets will be amortized over a weighted average useful life of 10 years.

Micreo Limited and Aerosim. On September 30, 2016, the Company acquired Micreo Limited (Micreo) and Flight Training Acquisitions LLC (Aerosim), in separate transactions, for an aggregate purchase price of approximately $86 million, which was financed with cash on hand. The purchase price and purchase price allocation of Micreo and Aerosim was finalized as of September 29, 2017, with no significant changes to preliminary amounts. Micreo specializes in solutions that utilize high-performance microwave, millimeter wave and photonic technology that complements the Company’s wide range of sensor products and is expected to strengthen the development of the Company’s future products in the higher Electronic Warfare (EW) radio frequency (RF) bandwidth. Micreo currently supports a variety of airborne, land and security programs in Australia. Aerosim provides innovative, portable and flexible pilot and maintenance technician training products and provides a flight school for prospective airline pilots. Aerosim’s commercial training capabilities are complementary to those offered by L3 Commercial Training Solutions. The aggregate goodwill recognized for these businesses was $59 million, which was assigned to the Electronic Systems and ISRS reportable segments, of which $6 million is expected to be deductible for income tax purposes.

Advanced Technical Materials, Inc. (ATM) Acquisition. On January 22, 2016, the Company acquired the assets of ATM for a purchase price of $27 million, which was financed with cash on hand. The purchase price and purchase price allocation of ATM was finalized as of September 23, 2016, with no significant changes to preliminary amounts. ATM develops and manufactures a broad product line of passive microwave waveguides and specialized coaxial components. The goodwill recognized for this business was $20 million, which was assigned to the C&NS reportable segment, all of which is expected to be deductible for income tax purposes.

2015 Business Acquisitions

ForceX, Inc. Acquisition. On October 13, 2015, the Company acquired ForceX, Inc., renamed L3 ForceX, for a purchase price of $61 million, which was financed with cash on hand. The purchase price and purchase price allocation of L3 ForceX was finalized as of September 23, 2016, with no significant changes to preliminary amounts. L3 ForceX specializes in ISR mission management software and geospatial application technology programs, offering an array of advanced products, including cueing system software, hardware and video algorithms, and wide-area sensor integration solutions and software. L3 ForceX’s proprietary processing, exploitation and dissemination capabilities provide an integrated tactical operational picture, allowing users to make critical decisions in real time. L3 ForceX also supports several key DoD ISR initiatives and classified programs. L3 ForceX’s customer base includes the USAF, U.S. Special Operations Command, the Naval Surface Warfare Center and a variety of DoD agencies. The goodwill recognized for this business was $53 million, which was assigned to the ISRS reportable segment, of which $52 million is expected to be deductible for income tax purposes.

CTC Aviation Group Acquisition. On May 27, 2015, the Company acquired CTC Aviation Group, renamed L3 CTC Ltd. (L3 CTC), for a purchase price of £153 million (approximately $236 million), which was financed with cash on hand. The purchase price and purchase price allocation of L3 CTC was finalized as of June 24, 2016, with no significant changes to preliminary amounts. L3 CTC is a global airline pilot training and crew resourcing specialist, based in the United Kingdom, which offers customized and innovative solutions to major airlines and flight training customers globally. L3 CTC expands L3’s commercial aviation training business to encompass a growing portfolio of airline and third-party training company customers. The goodwill recognized for this business was £118 million (approximately $182 million), which was assigned to the Electronic Systems reportable segment, and is not expected to be deductible for income tax purposes.

MITEQ, Inc. Acquisition. On January 21, 2015, the Company acquired the assets of MITEQ, Inc. (Miteq) for a purchase price of $41 million, which was financed with cash on hand. The purchase price and purchase price allocation of Miteq was finalized as of September 25, 2015, with no significant changes to preliminary amounts. Miteq was combined with the Company’s Narda Microwave-East business and the new organization was re-named L3 Narda-Miteq. Miteq offers a broad product line of active and passive RF microwave components and low-power satellite communications (SATCOM) products for space and military applications that complement the existing Narda Microwave East product line. The combined L3 Narda-Miteq business provides products for the DoD, other U.S. Government agencies, prime contractors and commercial customers. The goodwill recognized for this business was $11 million, of which $4 million is expected to be deductible for income tax purposes. The goodwill was assigned to the C&NS reportable segment.

Unaudited Pro Forma Statements of Operations Data

The following unaudited pro forma Statements of Operations data present the combined results of the Company and its business acquisitions completed during the years ended December 31, 2017 and 2016 assuming that the business acquisitions completed during 2017 and 2016 had occurred on January 1, 2016 and January 1, 2015, respectively. The unaudited pro forma Statements of Operations data below include adjustments for additional amortization expense related to acquired intangible assets and depreciation assuming the 2017 and 2016 acquisitions had occurred on January 1, 2016 and January 1, 2015, respectively.



	Year Ended December 31,
	2017		2016
	(in millions, except per share data)
Pro forma net sales	$	9,638	$	9,493
Pro forma income from continuing operations attributable to L3	$	753	$	621
Pro forma net income attributable to L3	$	677	$	712
Pro forma diluted earnings per share from continuing operations	$	9.46	$	7.88
Pro forma diluted earnings per share	$	8.51	$	9.03

The unaudited pro forma results disclosed in the table above are based on various assumptions and are not necessarily indicative of the results of operations that would have occurred had the Company completed these acquisitions on the dates indicated above.

Business Divestitures

2017 Divestitures

During the year ended December 31, 2017, the Company completed the sales of the CTC Aviation Jet Services Limited (Aviation Jet Services) business, the L3 Coleman Aerospace (Coleman) business and the Display Product Line. The table below presents pre-tax (loss) gain recognized, the proceeds received and net sales included in continuing operations from these divestitures.



	Year Ended December 31, 2017
	Pre-Tax (Loss) gain			Proceeds Received		Net Sales
	(in millions)
Aviation Jet Services divestiture	$	(5	)	$	1	$	1
Coleman divestiture	(3		)	17		9
Display Product Line divestiture	4			7		—
Total	$	(4	)	$	25	$	10

Aviation Jet Services Divestiture. On March 1, 2017, the Company divested its Aviation Jet Services business for a sales price of £1 million (approximately $1 million). Aviation Jet Services provided non-core aircraft management and operational services as part of commercial training solutions based in the United Kingdom and was included in the Electronic Systems segment.

Coleman Divestiture. On February 24, 2017, the Company divested its Coleman business for a sales price of $15 million. Coleman provided air-launch ballistic missile targets and was included in the Electronic Systems segment.

Display Product Line Divestiture. On February 23, 2017, the Company divested its Display Product Line for a sales price of $7 million. The Display Product Line provided cockpits to various military aircraft and was included in the Electronic Systems segment.

2016 Divestitures

NSS. On February 1, 2016, the Company completed the sale of its NSS segment to CACI International Inc. for a sales price of $547 million. See Discontinued Operations below for additional information.

2015 Business Divestitures

During the year ended December 31, 2015, the Company completed the sales of Marine Systems International (MSI), Broadcast Sports Inc. (BSI), the Tinsley Product Line and Klein Associates, Inc. (Klein). The table below presents pre-tax loss recognized, the proceeds received and net sales included in continuing operations from these business divestitures.



	Year Ended December 31, 2015
	Pre-Tax Loss			Proceeds Received		Net Sales
	(in millions)
MSI divestiture	$	(17	)	$	318	$	185
BSI divestiture	(4		)	26		7
Tinsley Product Line divestiture	(8		)	4		9
Klein divestiture	(2		)	10		8
Total	$	(31	)	$	358	$	209

MSI Divestiture. On May 29, 2015, the Company completed the sale of its MSI business to Wärtsilä Corporation for a sales price of €295 million (approximately $318 million), in addition to the assumption by Wärtsilä Corporation of approximately €60 million of MSI employee pension-related liabilities. The sales price was finalized as of June 24, 2016, with no significant changes to preliminary amounts. MSI was a sector within the Company’s Electronic Systems segment, primarily selling to the commercial shipbuilding industry.

BSI Divestiture. On April 24, 2015, the Company divested its BSI business for a sales price of $26 million. BSI provided wireless technology and communications systems services for use in the field of sports television broadcasting, and was included in the ISRS segment.

Tinsley Product Line Divestiture. On July 27, 2015, the Company divested its Tinsley Product Line for a sales price of $4 million. Tinsley provided optical components, sub-assemblies and passive sub-systems and was included in the ISRS segment.

Klein Divestiture. On December 31, 2015 the Company divested its Klein business for a sales price of $10 million. Klein provided side scan sonar equipment and waterside security and surveillance systems, and was included in the ISRS segment.

Net sales and income before income taxes for Aviation Jet Services, Coleman, the Display Product Line, MSI, BSI, the Tinsley Product Line and Klein, included in L3’s consolidated statements of operations, are presented in the table below on an aggregate basis, and are included in income from continuing operations for all periods presented.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Net sales	$	10	$	59	$	259
Income before income taxes	$	2	$	8	$	8

Discontinued Operations

Vertex Aerospace. As discussed in Note 1, on October 16, 2017, the Company’s Board of Directors approved a plan to explore strategic alternatives to sell or otherwise divest the Vertex Aerospace business. The Company expects to complete a sale in 2018. The divestiture of the Vertex Aerospace business is a strategic shift by the Company to exit the logistics solution and maintenance services business for military aircraft where the Company does not provide complex ISR systems integration and modification. The Vertex Aerospace business generated sales of $1.4 billion in 2017, $1.3 billion in 2016, and $1.2 billion in 2015. The assets and liabilities, and results of operations of the Vertex Aerospace business are reported as discontinued operations for all periods presented.

NSS. On February 1, 2016, the Company completed the sale of its NSS segment to CACI International Inc. for a sales price of $547 million. The results of operations NSS are reported as discontinued operations for all periods presented.

The table below presents the statements of operations data for Vertex Aerospace and NSS. The amounts presented in discontinued operations include allocated interest expenses for debt not directly attributable or related to L3’s other operations. Interest expense was allocated in accordance with the accounting standards for discontinued operations and were based on the ratio of their net assets to the sum of: (1) total L3 consolidated net assets and (2) L3 consolidated total debt.



	Year Ended December 31,
	2017			2016			2015
	(in millions)
Net sales	$	1,429		$	1,402		$	2,334
Cost of sales	(1,342		)	(1,357		)	(2,259		)
(Loss) gain related to business divestiture⁽¹⁾	(1		)	64			—
Goodwill impairment charges⁽²⁾	(187		)	—			(909		)
Operating (loss) income from discontinued operations	(101		)	109			(834		)
Interest expense allocated to discontinued operations	(2		)	(5		)	(26		)
(Loss) income from discontinued operations before income taxes	(103		)	104			(860		)
Income tax benefit (expense)	27			(13		)	128
(Loss) income from discontinued operations net of income taxes	$	(76	)	$	91		$	(732	)

__________________


⁽¹⁾	For the year ended December 31, 2017, the Company recognized $1 million of trailing expenses related to the sale of NSS. The year ended December 31, 2016 included a gain of $64 million (before and after income taxes) on the sale of NSS.


⁽²⁾	Due to a decline in estimated fair value, the Company recorded goodwill impairment charges for the years ended December 31, 2016 and 2015. The impairment charge of $187 million recorded during 2017 relates to Vertex Aerospace. The impairment charge of $909 million recorded during 2015 consists of: (i) $571 million related to NSS and (ii) $338 million related to Vertex Aerospace.

The major classes of assets and liabilities included in discontinued operations related to Vertex Aerospace are presented in the table below. As discussed above, since the sale of NSS was completed on February 1, 2016, the balances below do not reflect NSS. These balances have been classified as current as the sale is expected to be completed within one year and the proceeds are not expected to be used to pay down long-term debt.



	December 31, 2017		December 31, 2016
	(in millions)
Assets
Current assets	$	284	$	271
Property, plant and equipment, net	13		14
Goodwill	—		187
Other Intangible Assets	7		9
Other assets	2		—
Total assets of discontinued operations	$	306	$	481

Liabilities
Accounts payable, trade	$	63	$	16
Other current liabilities	131		160
Current liabilities	194		176
Long-term liabilities	32		59
Total liabilities of discontinued operations	$	226	$	235

Assets Held for Sale

Aerostructures. The Aerostructures businesses are classified as held for sale as of December 31, 2017. Aerostructures within the Company’s ISRS segment, primarily provides aircraft fabrication and assembly of fixed and rotary wing aero structures as well as avionics hardware and software systems to address mission critical needs. The major classes of assets and liabilities included as held for sale related to the Aerostructures businesses are presented in the table below.



	December 31, 2017

Assets
Billed receivables	$	14
Contracts in process	33
Total current assets	47
Property, plant and equipment, net	34
Goodwill	52
Identifiable intangible assets	2
Total assets classified as held for sale	$	135

Liabilities
Accounts payable, trade	$	3
Accrued employment costs	2
Accrued expenses	3
Other current liabilities	5
Total current liabilities	13
Deferred income taxes	4
Total liabilities classified as held for sale	$	17

Contracts in Process

12 Months Ended

Dec. 31, 2017

Contractors [Abstract]

Contracts in Process

. Contracts in Process

The components of contracts in process are presented in the table below. The unbilled contract receivables, inventoried contract costs and unliquidated progress payments principally relate to contracts with the U.S. Government and prime contractors or subcontractors of the U.S. Government.



	December 31,
	2017			2016
	(in millions)
Unbilled contract receivables, gross	$	1,874		$	1,890
Unliquidated progress payments	(761		)	(827		)
Unbilled contract receivables, net	1,113			1,063
Inventoried contract costs, gross	891			998
Unliquidated progress payments	(71		)	(203		)
Inventoried contract costs, net	820			795
Total contracts in process	$	1,933		$	1,858

Unbilled Contract Receivables. Unbilled contract receivables represent accumulated incurred costs and earned profits on contracts (revenue arrangements), which have been recorded as sales, but have not yet been billed to customers. Unbilled contract receivables arise from the cost-to-cost method of revenue recognition that is used to record sales on certain fixed-price contracts. Unbilled contract receivables from fixed-price type contracts are converted to billed receivables when amounts are invoiced to customers according to contractual billing terms, which generally occur when deliveries or other performance milestones are completed. Unbilled contract receivables also arise from cost-plus type contracts, time-and-material type contracts and fixed-price service type contracts for revenue amounts that have not been billed by the end of the accounting period due to the timing of preparation of invoices to customers. The Company believes that approximately 92% of the unbilled contract receivables, net at December 31, 2017 will be billed and collected within one year.

Unliquidated Progress Payments. Unliquidated progress payments arise from fixed-price type contracts with the U.S. Government that contain progress payment clauses, and represent progress payments on invoices that have been collected in cash, but have not yet been liquidated. Progress payment invoices are billed to the customer as contract costs are incurred at an amount generally equal to 80% of incurred costs. Unliquidated progress payments are liquidated as deliveries or other contract performance milestones are completed, at an amount equal to a percentage of the contract sales price for the items delivered or work performed, based on a contractual liquidation rate. Therefore, unliquidated progress payments are a contra asset account, and are classified against unbilled contract receivables if revenue for the underlying contract is recorded using the cost-to-cost method, and against inventoried contract costs if revenue is recorded using the units-of-delivery method.

Inventoried Contract Costs. In accordance with contract accounting standards, the Company’s U.S. Government contractor businesses account for the portion of their G&A, IRAD and B&P costs that are allowable and reimbursable indirect contract costs under U.S. Government procurement regulations on their U.S. Government contracts (revenue arrangements) as inventoried contract costs. G&A, IRAD and B&P costs are allocated to contracts for which the U.S. Government is the end customer and are charged to costs of sales when sales on the related contracts are recognized. The Company’s U.S. Government contractor businesses record the unallowable portion of their G&A, IRAD and B&P costs to expense as incurred, and do not include them in inventoried contract costs.

The table below presents a summary of G&A, IRAD and B&P costs included in inventoried contract costs and the changes to them, including amounts charged to cost of sales by the Company’s U.S. Government contractor businesses for the periods presented.



	Year Ended December 31,
	2017			2016			2015
	(in millions)
Amounts included in inventoried contract costs at beginning of the year	$	173		$	137		$	114
Contract costs incurred:
IRAD and B&P	333			304			280
Other G&A⁽¹⁾	842			749			742
Total	1,175			1,053			1,022
Amounts charged to operating costs and expenses	(1,179		)	(1,017		)	(999		)
Amounts included in inventoried contract costs at end of the year	$	169		$	173		$	137

__________________


⁽¹⁾	Amounts include severance and restructuring related costs of $91 million, $13 million and $14 million for the years ended December 31, 2017, 2016 and 2015, respectively.

The table below presents a summary of selling, general and administrative expenses and research and development expenses for the Company’s commercial businesses, which are expensed as incurred and included in cost of sales.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Selling, general and administrative expenses	$	278	$	223	$	261
Research and development expenses	63		54		52
Total	$	341	$	277	$	313

Inventories

12 Months Ended

Dec. 31, 2017

Inventory Disclosure [Abstract]

Inventories

. Inventories

Inventories at Lower of Cost or Realizable Value. The table below presents the components of inventories at the lower of cost (first-in, first-out or average cost) or realizable value.



	December 31,
	2017		2016
	(in millions)
Raw materials, components and sub-assemblies	$	184	$	165
Work in process	98		106
Finished goods	107		59
Total	$	389	$	330

Goodwill and Identifiable Intangible Assets

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Identifiable Intangible Assets

. Goodwill and Identifiable Intangible Assets

Goodwill. In accordance with the accounting standards for business combinations, the Company records the assets acquired and liabilities assumed based on their estimated fair values at the date of acquisition (commonly referred to as the purchase price allocation). Goodwill represents the purchase price paid in excess of the fair value of net tangible and intangible assets acquired. As part of the purchase price allocations for the Company’s business acquisitions, identifiable intangible assets are recognized as assets apart from goodwill if they arise from contractual or other legal rights, or if they are capable of being separated or divided from the acquired business and sold, transferred, licensed, rented or exchanged. However, the Company does not recognize any intangible assets apart from goodwill for the assembled workforces of its business acquisitions. At December 31, 2017, the Company had approximately 31,000 employees, and the substantial majority of the sales generated by the Company’s businesses were from the productive labor efforts of its employees, as compared to selling manufactured products or right-to-use technology.

Generally, the largest intangible assets from the businesses that the Company acquires are the assembled workforces, which includes the human capital of the management, administrative, marketing and business development, scientific, engineering and technical employees of the acquired businesses. The success of the Company’s businesses, including their ability to retain existing business (revenue arrangements) and to successfully compete for and win new business (revenue arrangements), is primarily dependent on the management, marketing and business development, contracting, engineering and technical skills and knowledge of its employees, rather than on productive capital (plant and equipment, and technology and intellectual property). Additionally, for a significant portion of its businesses, the Company’s ability to attract and retain employees who have U.S. Government security clearances, particularly those of top-secret and above, is critical to its success, and is often a prerequisite for retaining existing revenue arrangements and pursuing new ones. Generally, patents, trademarks and licenses are not material for the Company’s acquired businesses. Furthermore, the Company’s U.S. Government contracts (revenue arrangements) generally permit other companies to use the Company’s patents in most domestic work performed by such other companies for the U.S. Government. Therefore, because intangible assets for assembled workforces are part of goodwill in accordance with the accounting standards for business combinations, the substantial majority of the intangible assets for the Company’s business acquisitions is recognized as goodwill. Additionally, the value assigned to goodwill for the Company’s business acquisitions also includes the value that the Company expects to realize from cost reduction measures that it implements for its acquired businesses.

The table below presents the changes in goodwill allocated to the Company’s reporting units in each reportable segment.



	ISRS			C&NS			Electronic Systems			Consolidated Total
	(in millions)
December 31, 2015
Goodwill	$	2,493		$	1,860		$	1,846		$	6,199
Accumulated impairment losses	(46		)	(15		)	(43		)	(104		)
	2,447			1,845			1,803			6,095
Business acquisitions⁽¹⁾	28			20			287			335
Foreign currency translation adjustments	(9		)	3			(50		)	(56		)

December 31, 2016
Goodwill	2,512			1,883			2,083			6,478
Accumulated impairment losses	(46		)	(15		)	(43		)	(104		)
	2,466			1,868			2,040			6,374
Business acquisitions⁽¹⁾	8			73			131			212
Business divestitures⁽²⁾	—			—			(12		)	(12		)
Foreign currency translation adjustments	26			21			46			93
Assets held for sale⁽³⁾	(42		)	—			(10		)	(52		)

December 31, 2017
Goodwill	2,504			1,977			2,238			6,719
Accumulated impairment losses	(46		)	(15		)	(43		)	(104		)
	$	2,458		$	1,962		$	2,195		$	6,615

__________________

⁽¹⁾

For the year ended December 31, 2017, business acquisitions for the ISRS segment included primarily the Kigre business acquisition. Business acquisitions for the C&NS segment included primarily the Adaptive Methods, Open Water Power, and OceanServer business acquisitions. Business acquisitions for the Electronic Systems segment included the acquisitions of the ETD, Doss Aviation and G-Air businesses and the purchase price allocation adjustments for the MacH and Aerosim business acquisitions. For the year ended December 31, 2016, business acquisitions for the ISRS segment included the Micreo business acquisition and the final purchase price allocation for the L3 ForceX business acquisition. Business acquisition for the C&NS segment included the ATM business acquisition. Business acquisitions for the Electronic Systems segment included the acquisitions of the MacH and Aerosim businesses and the final purchase price allocation for L3 CTC business acquisition.


⁽²⁾	The decrease for the Electronic Systems segment was due to the divestitures of Coleman and Aviation Jet Services during the quarterly period ended March 31, 2017.


⁽³⁾	The Aerostructures businesses from the Company’s ISRS segment are classified as held for sale as of December 31, 2017.

Identifiable Intangible Assets. The most significant identifiable intangible asset that is separately recognized for the Company’s business acquisitions is customer contractual relationships. All of the Company’s customer relationships are established through written customer contracts (revenue arrangements). The fair value for customer contractual relationships is determined, as of the date of acquisition, based on estimates and judgments regarding expectations for the estimated future after-tax earnings and cash flows (including cash flows for working capital) arising from the follow-on sales on contract (revenue arrangement) renewals expected from the customer contractual relationships over their estimated lives, including the probability of expected future contract renewals and sales, less a contributory assets charge, all of which is discounted to present value. The Company’s indefinite-lived intangible assets include IPR&D.

The table below presents information for the Company’s identifiable intangible assets that are subject to amortization and indefinite-lived intangible assets.



		December 31, 2017						December 31, 2016
	Weighed Average Amortization Period	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
	(in years)	(in millions)
Customer contractual relationships	14	$	393	$	257	$	136	$	360	$	229	$	131
Technology	10	189		114		75		191		102		89
Other	15	29		14		15		21		12		9
Total subject to amortization		611		385		226		572		343		229
IPR&D	indefinite	66		—		66		—		—		—
Total		$	677	$	385	$	292	$	572	$	343	$	229

The table below presents amortization expense recorded by the Company for its identifiable intangible assets.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Amortization expense	$	43	$	33	$	32

Based on gross carrying amounts at December 31, 2017, the Company’s estimate of amortization expense for identifiable intangible assets for the years ending December 31, 2018 through 2022 is presented in the table below.



	Year Ending December 31,
	2018		2019		2020		2021		2022
	(in millions)
Estimated amortization expense	$	44	$	39	$	31	$	25	$	21

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Other Current Liabilities and Other Liabilities

12 Months Ended

Dec. 31, 2017

Other Liabilities Disclosure [Abstract]

Other Current Liabilities and Other Liabilities

. Other Current Liabilities and Other Liabilities

The table below presents the components of other current liabilities.



	December 31,
	2017		2016
	(in millions)
Other Current Liabilities:
Accrued product warranty costs	$	69	$	68
Estimated costs in excess of estimated contract value to complete contracts in process in a loss position	63		70
Accrued interest	43		43
Deferred revenues	38		34
Estimated contingent purchase price payable for acquired businesses (see Note 3)	11		—
Accruals for pending and threatened litigation	3		14
Other	140		163
Total other current liabilities	$	367	$	392

The table below presents the components of other liabilities.



	December 31,
	2017		2016
	(in millions)
Other Liabilities:
Non-current income taxes payable (see Note 16)	$	164	$	121
Deferred compensation	49		47
Accrued product warranty costs	30		41
Accrued workers’ compensation	23		25
Estimated contingent purchase price payable for acquired businesses (see Note 3)	20		29
Notes payable and capital lease obligations	16		10
Other	96		83
Total other liabilities	$	398	$	356

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

. Property, Plant and Equipment

The table below presents the components of property, plant and equipment.



	December 31,
	2017			2016
	(in millions)
Land	$	34		$	53
Buildings and improvements	404			437
Machinery, equipment, furniture and fixtures	1,959			1,857
Leasehold improvements	376			337
Gross property, plant and equipment	2,773			2,684
Accumulated depreciation and amortization	(1,663		)	(1,577		)
Property, plant and equipment, net	$	1,110		$	1,107

Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt

. Debt

The components of debt and a reconciliation to the carrying amount of long-term debt is presented in the table below.



	December 31,
	2017			2016
	(in millions)
Borrowings under Revolving Credit Facility⁽¹⁾	$	—		$	—
5.20% Senior Notes due 2019	1,000			1,000
4.75% Senior Notes due 2020	800			800
4.95% Senior Notes due 2021	650			650
3.95% Senior Notes due 2024	350			350
3.85% Senior Notes due 2026	550			550
Principal amount of long-term debt	3,350			3,350
Unamortized discounts	(7		)	(8		)
Deferred debt issue costs	(13		)	(17		)
Carrying amount of long-term debt	$	3,330		$	3,325

__________________


⁽¹⁾	During 2017, L3's aggregate borrowings and repayments under the Credit Facility were $1,328 million. L3 had the full availability of its $1 billion Credit Facility at December 31, 2017 and December 31, 2016.

L3 Revolving Credit Facility

On October 31, 2016, L3 entered into a new five year unsecured revolving credit facility (Credit Facility), which replaced its amended and restated revolving credit agreement dated February 3, 2012. The Credit Facility provides for total aggregate borrowings of $1 billion and any outstanding borrowings under the Credit Facility are due and payable on October 31, 2021. Borrowings under the Credit Facility may consist of: (1) base rate loans, which shall bear interest at a rate equal to the sum of the applicable rate (as defined in the Credit Facility), and the “base rate” (as defined in the Credit Facility) and/or (2) eurodollar loans, which shall bear interest at a rate equal to the sum of the applicable rate plus the “Eurodollar rate” (as defined in the Credit Facility). The applicable rate for base rate loans under the Credit Facility ranges from 0.125% to 1.000%, and the applicable rate for eurodollar loans ranges from 1.125% to 2.000%, in each case based on the long-term debt rating of L3. In addition, the Credit Facility provides for uncommitted incremental revolving facilities and additional term loan facilities in an aggregate principal amount of up to $600 million.

L3 Senior Notes

The Senior Notes are unsecured senior obligations of L3. The terms of each outstanding Senior Note are presented in the table below.



Note	Date of Issuance		Amount Issued		Discount⁽¹⁾		Net Cash Proceeds		Effective Interest Rate		Redemption at Treasury Rate⁽²⁾⁽³⁾
		(in millions)
5.20% Senior Notes due October 15, 2019	October 2, 2009		$	1,000	$	4	$	987	5.25	%	30 bps
4.75% Senior Notes due July 15, 2020	May 21, 2010		$	800	$	3	$	790	4.79	%	25 bps
4.95% Senior Notes due February 15, 2021	February 7, 2011		$	650	$	4	$	639	5.02	%	25 bps
3.95% Senior Notes due May 28, 2024	May 28, 2014		$	650	$	3	$	641	4.02	%	20 bps
3.85% Senior Notes due December 15, 2026	December 5, 2016		$	550	$	3	$	542	3.91	%	25 bps

__________________


⁽¹⁾	Bond discounts are recorded as a reduction to the principal amount of the notes and are amortized as interest expense over the term of the notes.

⁽²⁾

The Senior Notes maturing in 2019 and 2020 may be redeemed at any time prior to their maturity and the Senior Notes maturing in 2021, 2024 and 2026 may be redeemed at any time prior to November 15, 2020, February 28, 2024 and September 15, 2026, respectively, (three months prior to their maturity) at the option of L3, in whole or in part, at a redemption price equal to the greater of: (1) 100% of the principal amount, or (2) the present value of the remaining principal and interest payments discounted to the date of redemption, on a semi-annual basis, at the Treasury Rate (as defined in the indentures governing the Senior Notes), plus the spread indicated in the table above. In addition, if the Senior Notes maturing in 2021, 2024 and 2026 are redeemed at any time on or after November 15, 2020, February 28, 2024 and September 15, 2026, respectively, the redemption price would be equal to 100% of the principal amount.


⁽³⁾	Upon the occurrence of a change in control (as defined in the indentures governing the Senior Notes), each holder of the notes will have the right to require L3 to repurchase all or any part of such holder’s notes at an offer price in cash equal to 101% of the aggregate principal amount plus accrued and unpaid interest, if any, to the date of purchase.

Repurchases, Redemptions and Maturities of Senior Notes

The repurchases, redemptions and maturities of Senior Notes are presented in the table below.



Note	Settlement Type	Date Settled	Aggregate Amount		Debt Retirement Charge		Cash Payments
			(in millions)
1.50% Senior Notes due 2017⁽¹⁾	Redemption	December 30, 2016	$	350	$	2	$	351
3.95% Senior Notes due 2016	Maturity	November 15, 2016	$	200	$	—	$	200
3.95% Senior Notes due 2016⁽²⁾	Redemption	May 20, 2016	$	300	$	5	$	305
3.95% Senior Notes due 2024	Tender Offer	December 22, 2015	$	300	$	1	$	297

__________________


⁽¹⁾	The 1.50% Senior Notes due 2017 were redeemed at a price equal to 100.323% of the principal amount thereof, plus accrued and unpaid interest to the redemption date. Interest ceased to accrue on and after the redemption date.


⁽²⁾	The 3.95% Senior Notes due 2016 were redeemed at a price equal to 101.475% of the principal amount thereof, plus accrued and unpaid interest. Interest ceased to accrue on and after May 20, 2016, and the only remaining right of holders of such Notes was to receive payment of the redemption price and accrued interest.

Guarantees

The borrowings under the Credit Facility are fully and unconditionally guaranteed by L3 and by substantially all of the material 100% owned domestic subsidiaries of L3 on an unsecured senior basis. The payment of principal and premium, if any, and interest on the Senior Notes is fully and unconditionally guaranteed, on an unsecured senior basis, jointly and severally, by L3’s material 100% owned domestic subsidiaries that guarantee any of its other indebtedness. See Note 24.

Subordination

The guarantees of the Credit Facility and the Senior Notes rank pari passu with each other.

Covenants

Financial and other restrictive covenants. The Credit Facility contains financial and other restrictive covenants that limit, among other things, the ability of the subsidiaries of L3 to borrow additional funds, and the ability of L3 and its subsidiaries to incur liens, make investments, merge or consolidate or dispose of assets. The Company’s Credit Facility contains covenants that require that: (1) the Company’s consolidated interest coverage ratio be greater than or equal to 3.0 to 1.0, (2) the Company’s consolidated leverage ratio be less than or equal to 3.75 to 1.0, provided that the foregoing consolidated leverage ratio shall be increased to 4.0 to 1.0 as of the end of each of the four fiscal quarters immediately following a material acquisition (as defined in the Credit Facility). Calculations of the financial covenants are to exclude, among other things, certain items such as impairment losses on goodwill or other intangible assets, non-cash gains or losses from discontinued operations, gains or losses in connection with asset dispositions, and gains or losses with respect to judgments or settlements in connection with litigation matters. At December 31, 2017, the Company was in compliance with its financial and other restrictive covenants.

The indentures governing the Senior Notes (Senior Indentures) contain covenants customary for investment grade notes, including covenants that restrict the ability of L3 and its 100% owned domestic subsidiaries to create, incur, assume or permit to exist any lien, except permitted liens (as defined in the Senior Indentures) and restrict the ability of L3 and its subsidiaries to enter into certain sale and leaseback transactions (as defined in the Senior Indentures).

Cross default provisions. The Credit Facility contains cross default provisions that are triggered when a payment default occurs or certain other defaults occur that would allow the acceleration of indebtedness, swap contracts or guarantees of L3 or its subsidiaries, so long as the aggregate amount of such indebtedness, swap contracts or guarantees is at least $75 million and such defaults (other than payment defaults and defaults that have resulted in acceleration) have not been cured within 10 days. The Senior Notes indenture contains a cross acceleration provision that is triggered when a default or acceleration occurs under any indenture or instrument of L3 or its subsidiaries or the payment of which is guaranteed by L3 or its subsidiaries in an aggregate amount of at least $100 million.

Accumulated Other Comprehensive (Loss) Income (AOCI)

12 Months Ended

Dec. 31, 2017

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Accumulated Other Comprehensive (Loss) Income (AOCI)

. Accumulated Other Comprehensive (Loss) Income (AOCI)

The changes in the AOCI balances, including amounts reclassified from AOCI into net income, are presented in the table below.



	Foreign currency translation			Unrealized (losses) gains on hedging instruments			Unrecognized (losses) gains and prior service cost, net			Total accumulated other comprehensive loss
	(in millions)
Balance at December 31, 2014	$	19		$	(5	)	$	(598	)	$	(584	)
Other comprehensive (loss) income before reclassifications, net of tax	(161		)	(15		)	81			(95		)
Amounts reclassified from AOCI, net of tax	41			12			52			105
Net current period other comprehensive (loss) income	(120		)	(3		)	133			10
Balance at December 31, 2015	$	(101	)	$	(8	)	$	(465	)	$	(574	)

Other comprehensive (loss) income before reclassifications, net of tax	(77		)	3			(119		)	(193		)
Amounts reclassified from AOCI, net of tax	—			11			30			41
Net current period other comprehensive (loss) income	(77		)	14			(89		)	(152		)
Balance at December 31, 2016	$	(178	)	$	6		$	(554	)	$	(726	)

Other comprehensive income (loss) before reclassifications, net of tax	124			7			(137		)	(6		)
Amounts reclassified from AOCI, net of tax	—			(4		)	45			41
Net current period other comprehensive income (loss)	124			3			(92		)	35
Balance at December 31, 2017	$	(54	)	$	9		$	(646	)	$	(691	)

Further details regarding the amounts reclassified from AOCI into net income are presented in the table below.



	Amount Reclassified from AOCI^(a)									Affected Line Item in the Audited Consolidated Statements of Operations
	Year Ended December 31,
Details About AOCI Components	2017			2016			2015
	(in millions)
Foreign currency translation adjustments:
MSI divestiture	$	—		$	—		$	(41	)	Loss related to business divestitures
	—			—			(41		)	Income from continuing operations before income taxes
	$	—		$	—		$	(41	)	Income from continuing operations

Gain (loss) on hedging instruments:
MSI divestiture	$	—		$	—		$	(2	)	Loss related to business divestitures
Other	5			(13		)	(16		)	Cost of sales-products
	5			(13		)	(18		)	Income from continuing operations before income taxes
	(1		)	2			6			Provision for income taxes
	$	4		$	(11	)	$	(12	)	Income from continuing operations

Amortization of defined benefit pension and postretirement items:
MSI divestiture	$	—		$	—		$	(14	)	Loss related to business divestitures
Net loss^(b)	(59		)	(48		)	(67		)
	(59		)	(48		)	(81		)	Income from continuing operations before income taxes
	14			18			29			Provision for income taxes
	$	(45	)	$	(30	)	$	(52	)	Income from continuing operations
Total reclassification for the period	$	(41	)	$	(41	)	$	(105	)	Income from continuing operations

__________________


^(a)	Amounts in parentheses indicate charges to the consolidated statements of operations.


^(b)	Amounts related to pension and postretirement benefit plans were reclassified from AOCI and recorded as a component of net periodic benefit cost (see Note 19 for additional information).

Equity	12 Months Ended
Equity	Dec. 31, 2017
Equity [Abstract]
Equity	. Equity On December 4, 2014, L3’s Board of Directors approved a share repurchase program that authorized L3 to repurchase up to $1.5 billion of its common stock which expired on June 30, 2017. On May 8, 2017, L3’s Board of Directors approved a new share repurchase program that authorizes L3 to repurchase up to an additional $1.5 billion of its common stock. The new program became effective on July 1, 2017 and has no set expiration date. Repurchases of L3’s common stock are made from time to time at management’s discretion in accordance with applicable U.S. Federal securities laws. The timing and actual number of shares to be repurchased in the future will depend on a variety of factors, including, but not limited to, the Company’s financial position, earnings, legal requirements, other investment opportunities (including acquisitions) and market conditions. L3 repurchased 1.0 million shares of its common stock at an average price of $183.67 per share for an aggregate amount of $180 million from January 1, 2017 through December 31, 2017. All share repurchases of L3’s common stock have been recorded as treasury shares. From January 1, 2018 through February 16, 2018, L3 repurchased 433,039 shares of its common stock at an average price of $203.33 per share for an aggregate amount of approximately $88 million. On February 12, 2018, L3’s Board of Directors declared a quarterly cash dividend of $0.80 per share, payable on March 15, 2018 to shareholders of record at the close of business on March 1, 2018. During the year ended December 31, 2017, the Company paid $236 million of cash dividends.

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

. Fair Value Measurements

Fair value is defined as the price that would be received for an asset or the exit price that would be paid to transfer a liability in the principal or most advantageous market in an orderly transaction between market participants. The standards establish a fair value hierarchy that gives the highest priority to observable inputs and the lowest priority to unobservable inputs.

The following table presents the fair value hierarchy level for each of the Company’s assets and liabilities that are measured and recorded at fair value on a recurring basis.



	December 31, 2017						December 31, 2016
Description	Level 1⁽¹⁾		Level 2⁽²⁾		Level 3⁽³⁾		Level 1⁽¹⁾		Level 2⁽²⁾		Level 3⁽³⁾
	(in millions)
Assets
Cash equivalents	$	310	$	—	$	—	$	104	$	—	$	—
Derivatives (foreign currency forward contracts)	—		11		—		—		12		—
Total assets	$	310	$	11	$	—	$	104	$	12	$	—

Liabilities
Derivatives (foreign currency forward contracts)	$	—	$	1	$	—	$	—	$	6	$	—
Contingent consideration⁽⁴⁾	—		—		31		—		—		29
Total liabilities	$	—	$	1	$	31	$	—	$	6	$	29

__________________


⁽¹⁾	Level 1 is based on quoted market prices available in active markets for identical assets or liabilities as of the reporting date. Cash equivalents are primarily held in registered money market funds, which are valued using quoted market prices.


⁽²⁾	Level 2 is based on pricing inputs other than quoted prices in active markets, which are either directly or indirectly observable. The fair value is determined using a valuation model based on observable market inputs, including quoted foreign currency forward exchange rates and consideration of non-performance risk.


⁽³⁾	Level 3 is based on pricing inputs that are not observable and not corroborated by market data.

⁽⁴⁾

The contingent consideration liability represents the future potential earn-out payments relating to the MacH and Open Water Power acquisitions. The fair value of the MacH contingent consideration liability is based on a Monte Carlo Simulation of the aggregate revenue of MacH for the three-year period ending December 31, 2019. The significant unobservable inputs used in calculating the fair value of the MacH contingent consideration include: (i) projected revenues of the MacH acquired business, (ii) company specific risk premium, which is a component of the discount rate applied to the revenue projections and (iii) volatility. The fair value of the Open Water Power contingent consideration liability is based on the Scenario-Based Method of the income approach using post-acquisition milestone achievements of Open Water Power through December 31, 2020. The significant unobservable inputs used in calculating the fair value of the Open Water Power contingent consideration include: (i) timing of achieving the milestones associated with the contingent consideration arrangement, (ii) probabilities of achieving each milestone and (iii) discount rate. The fair value of the contingent consideration for potential earn-out payments is reassessed quarterly, including an analysis of the significant inputs used in the evaluation, as well as the accretion of the present value discount. Changes are reflected within cost of sales in the consolidated statements of operations.

The table below presents the changes to contingent consideration obligations during the year ended December 31, 2017.



	December 31, 2017
	(in millions)
Balance at beginning of period	$	29
Acquisitions	14
Changes in fair value of contingent consideration, net	(12		)
Balance at end of period	$	31

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Financial Instruments

12 Months Ended

Dec. 31, 2017

Investments, All Other Investments [Abstract]

Financial Instruments

. Financial Instruments

At December 31, 2017 and 2016, the Company’s financial instruments consisted primarily of cash and cash equivalents, billed receivables, trade accounts payable, Senior Notes and foreign currency forward contracts. The carrying amounts of cash and cash equivalents, billed receivables and trade accounts payable are representative of their respective fair values because of the short-term maturities or expected settlement dates of these instruments. The carrying amounts and estimated fair values of the Company’s other financial instruments are presented in the table below.



	December 31, 2017				December 31, 2016
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
	(in millions)
Senior Notes⁽¹⁾	$	3,330	$	3,502	$	3,325	$	3,526
Foreign currency forward contracts⁽²⁾	$	10	$	10	$	6	$	6

__________________


⁽¹⁾	The Company measures the fair value of its Senior Notes using Level 2 inputs based primarily on current market yields for its existing debt traded in the secondary market.


⁽²⁾	The Company measures the fair values of foreign currency forward contracts based on forward exchange rates. See Note 14 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts.

Derivative Financial Instruments

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

. Derivative Financial Instruments

Notional amounts are used to measure the volume of foreign currency forward contracts and do not represent exposure to foreign currency losses. The table below presents the notional amounts of the Company’s outstanding foreign currency forward contracts by currency at December 31, 2017.



Currency	Notional Amount
	(in millions)
U.S. dollar	$	108
Canadian dollar	100
Euro	84
British pound	15
Total	$	307

At December 31, 2017, the Company’s foreign currency forward contracts had maturities through 2023.

The table below presents the location of the Company’s derivative instruments recorded at fair value on the consolidated balance sheets.



	December 31, 2017								December 31, 2016
	Other Current Assets		Other Assets		Other Current Liabilities		Other Liabilities		Other Current Assets		Other Assets		Other Current Liabilities		Other Liabilities
	(in millions)
Derivatives designated as hedging instruments:
Foreign currency forward contracts⁽¹⁾	$	11	$	—	$	1	$	—	$	10	$	2	$	6	$	—
Total derivative instruments	$	11	$	—	$	1	$	—	$	10	$	2	$	6	$	—

__________________


⁽¹⁾	See Note 12 for a description of the fair value hierarchy related to the Company's foreign currency forward contracts.

The effects from foreign currency forward contracts on the consolidated statements of operations were a pre-tax gain of $5 million for the year ended December 31, 2017, a pre-tax loss of $13 million for the year ended December 31, 2016, and a pre-tax loss of $18 million for the year ended December 31, 2015. At December 31, 2017, the estimated net amount of existing gains that are expected to be reclassified into income within the next 12 months is $2 million.

L3's Earnings Per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

L3's Earnings Per Share

. L3’s Earnings Per Share

A reconciliation of basic and diluted earnings per share (EPS) is presented in the table below.



	Year Ended December 31,
	2017			2016			2015
	(in millions, except per share data)
Reconciliation of net income (loss):
Net income (loss)	$	693		$	724		$	(225	)
Net income from continuing operations attributable to noncontrolling interests	(16		)	(14		)	(15		)
Net income (loss) attributable to L3’s common shareholders	$	677		$	710		$	(240	)
Earnings (loss) attributable to L3’s common shareholders:
Continuing operations	$	753		$	619		$	492
Discontinued operations, net of income tax	(76		)	91			(732		)
Net income (loss) attributable to L3’s common shareholders	$	677		$	710		$	(240	)
Earnings (loss) per share attributable to L3’s common shareholders:
Basic:
Weighted average common shares outstanding	78.0			77.4			80.7
Basic earnings (loss) per share:
Continuing operations	$	9.65		$	7.99		$	6.10
Discontinued operations, net of income tax	(0.97		)	1.18			(9.07		)
Net income (loss)	$	8.68		$	9.17		$	(2.97	)
Diluted:
Common and potential common shares:
Weighted average common shares outstanding	78.0			77.4			80.7
Effect of dilutive securities	1.6			1.4			1.2
Common and potential common shares	79.6			78.8			81.9
Diluted earnings (loss) per share:
Continuing operations	$	9.46		$	7.86		$	6.01
Discontinued operations, net of income tax	(0.95		)	1.15			(8.94		)
Net income (loss)	$	8.51		$	9.01		$	(2.93	)

The computation of diluted EPS excludes 0.3 million, 0.4 million and 0.6 million shares for the years ended December 31, 2017, 2016 and 2015, respectively, for share-based payment awards as they were anti-dilutive.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

. Income Taxes

On December 22, 2017, the U.S. Government enacted the U.S. Tax Cuts and Jobs Act (U.S. Tax Reform), which made significant changes to the U.S. tax system. Significant changes under U.S. Tax Reform include, among other things, the reduction of the U.S. corporate income tax rate from 35% to 21%, the implementation of a modified territorial tax system, and the imposition of a one-time repatriation tax on deemed repatriated earnings and profits of U.S. owned foreign subsidiaries (Toll Charge).

The Company recognized the income tax effects of U.S. Tax Reform in accordance with the Securities and Exchange Commission Staff Accounting Bulletin No. 118, Income Tax Accounting Implication of the Tax Cuts and Job Act (SAB 118), in its consolidated financial statements for the year ended December 31, 2017. SAB 118 provides guidance for the application of income tax accounting standards related to U.S. Tax Reform. Accordingly, the consolidated financial statements reflect the income tax effects of U.S. Tax Reform for which the accounting is incomplete but a reasonable estimate could be determined. The Company recorded an estimated tax benefit of $79 million from U.S. Tax Reform, which includes a $101 million estimated tax benefit related to the remeasurement of deferred taxes partially offset by an estimated tax provision of $22 million related to the Toll Charge. The preliminary tax benefit recorded may differ in the future due principally to changes to the interpretations of U.S. Tax Reform, legislative action to clarify the interpretation of U.S. Tax Reform and changes to estimates the Company has utilized to calculate the tax benefit. The Company expects to finalize the tax benefit from U.S. Tax Reform with the filing of its tax return and record the difference between the final benefit and the provisional benefit recorded in the 2018 fourth quarter, if any, at that time.

Income from continuing operations before income taxes is summarized in the table below.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Domestic	$	649	$	608	$	509
Foreign	222		196		130
Income from continuing operations before income taxes	$	871	$	804	$	639

The components of the Company’s current and deferred portions of the provision for income taxes on continuing operations are presented in the table below.



	Year Ended December 31,
	2017			2016		2015
	(in millions)
Current income tax provision:
Federal	$	44		$	88	$	81
State and local	10			8		7
Foreign	56			48		26
Subtotal	110			144		114

Deferred income tax provision/(benefit):
Federal	(16		)	25		9
State and local	6			2		7
Foreign	2			—		2
Subtotal	(8		)	27		18
Total provision for income taxes	$	102		$	171	$	132

A reconciliation of the statutory federal income tax rate to the effective income tax rate on continuing operations of the Company is presented in the table below.



	Year Ended December 31,
	2017		2016		2015
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%
State and local income taxes, net of federal income tax benefit	2.0		2.0		2.0
Foreign income taxes	(6.7	)	(3	)	(7.1	)
Manufacturing benefits	(1.4	)	(2.2	)	(2.2	)
Research and experimentation and other tax credits	(4.1	)	(4.6	)	(6.5	)
Resolution of tax contingencies	(0.4	)	(3.1	)	(1.4	)
Tax deductible dividends	(0.9	)	(1	)	(1.2	)
Equity compensation - excess income tax benefits	(2.3	)	(2.1	)	—
Goodwill impairment	—		—		1.9
Tax Reform	(9.1	)	—		—
Other, net	(0.4	)	0.3		0.2
Effective income tax rate on continuing operations	11.7	%	21.3	%	20.7	%

The significant components of the Company’s net deferred tax assets and liabilities are presented in the table below.



	December 31,
	2017			2016
	(in millions)
Deferred tax assets:
Inventoried costs	$	44		$	53
Compensation and benefits	94			139
Pension and postretirement benefits	281			413
Loss carryforwards	12			19
Tax credit carryforwards	5			6
Other	57			87
Deferred tax assets	493			717
Less: valuation allowance	(10		)	(12		)
Deferred tax assets, net of valuation allowance	483			705
Deferred tax liabilities:
Goodwill and other intangible assets	$	(514	)	$	(722	)
Income recognition on contracts in process	(24		)	(22		)
Property, plant and equipment	(59		)	(93		)
Other	(41		)	(55		)
Deferred tax liabilities	(638		)	(892		)
Total deferred tax liabilities, net of valuation allowance	$	(155	)	$	(187	)

The classification of the Company’s deferred tax assets and liabilities are presented in the table below.



	December 31,
	2017			2016
	(in millions)
Non-current deferred tax assets	$	3		$	2
Non-current deferred tax liabilities	(158		)	(189		)
Total net deferred tax liabilities	$	(155	)	$	(187	)

Non-current deferred tax assets are presented in other assets on the consolidated balance sheets.

The following table presents the Company’s loss and tax credit carryforwards at December 31, 2017 on a tax return basis. The Company has established a valuation allowance as indicated in those instances in which it does not believe that it is more likely than not it will generate sufficient taxable income, of the appropriate character and in the applicable subsidiary, to utilize the carryforwards.



	Year Ended December 31, 2017
	Carryforwards				Valuation Allowances
	Gross		Tax Effected		Gross			Tax Effected			Expiration Periods
	(in millions)
Federal net operating loss carryforwards	$	29	$	6	$	(5	)	$	(1	)	2026-2036
Foreign net operating loss carryforwards	12		3		(6		)	(2		)	Indefinite
State net operating loss carryforwards	160		3		(135		)	(2		)	2018-2037
Total loss carryforwards			$	12				$	(5	)

State tax credit carryforwards	6		5		(5		)	(4		)	2018-2032
Total tax credit carryforwards			$	5				$	(4	)

At December 31, 2017, the total amount of unrecognized tax benefits was $178 million, $157 million of which would reduce the effective income tax rate, if recognized. A reconciliation of the change in unrecognized income tax benefits, excluding potential interest and penalties, is presented in the table below.



	2017			2016			2015
	(in millions)
Balance at January 1	$	110		$	124		$	150
Additions for tax positions related to the current year	14			16			14
Additions for tax positions related to prior years	66			2			2
Reductions for tax positions related to prior years	(4		)	(24		)	(34		)
Reductions for tax positions related to settlements with taxing authorities	—			(1		)	(1		)
Reduction for tax positions related to prior years as a result of a lapse of statute of limitations	(8		)	(7		)	(7		)
Balance at December 31	$	178		$	110		$	124

The Company and its subsidiaries file income tax returns in the U.S. Federal jurisdiction, which is the Company’s primary tax jurisdiction, and various state and foreign jurisdictions. At December 31, 2017, the statutes of limitations for the Company’s U.S. Federal income tax returns for the years ended December 31, 2012 through 2016 were open. The U.S. Internal Revenue Service (IRS) commenced audits of the Company’s U.S. Federal income tax returns for the years ended 2012 and 2013. The Company cannot predict the outcome of the audits at this time. At December 31, 2017, the Company anticipates that unrecognized tax benefits will decrease by approximately $6 million over the next 12 months due to the potential resolution of unrecognized tax benefits involving several jurisdictions and tax periods. The actual amount of the decrease over the next 12 months could vary significantly depending on the ultimate timing and nature of any settlements.

During the years ended December 31, 2017, 2016 and 2015, the Company effectively settled various Federal, state and local and foreign audits. As a result of these settlements, the Company reversed previously accrued income tax expense of $4 million, $25 million and $9 million, including interest and penalties.

At December 31, 2017 and 2016, current and non-current income taxes payable include accrued potential interest of $15 million ($11 million after income taxes) and $11 million ($7 million after income taxes), respectively, and potential penalties of $8 million and $7 million, respectively. With respect to the interest related items, the Company’s income tax expense included an expense of $5 million for the year ended December 31, 2017 and a benefit of $3 million for the year ended December 31, 2016.

Prior to 2015, the Company recorded a deferred tax liability related to the repatriation of earnings from certain subsidiaries. During 2015, the Company completed a legal restructuring of its significant foreign operations, and the earnings of these subsidiaries are now considered reinvested indefinitely. As a result, the Company recognized a $17 million deferred tax benefit in the year ended December 31, 2015. At December 31, 2017, the Company had not provided deferred income taxes and foreign withholding taxes for $844 million of undistributed earnings by its non-U.S. subsidiaries as such earnings are intended to be reinvested indefinitely. Quantification of additional taxes that may be payable on distribution is not practicable.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

. Stock-Based Compensation

Stock-Based Compensation Plans. The Company has adopted stock-based compensation plans in order to provide incentives to directors, officers, employees and other individuals providing services to or on behalf of the Company and its subsidiaries. The Company believes that its stock-based compensation awards encourage high levels of performance by individuals who contribute to the success of the Company and enable the Company to attract, retain and reward talented and experienced individuals. This is accomplished by providing eligible individuals with an opportunity to obtain or increase a proprietary interest in the Company and/or by providing eligible individuals with additional incentives to join or remain with the Company. The stock-based compensation plans serve to better align the interests of management and its employees with those of the Company’s shareholders. During the year ended December 31, 2017, the Company awarded stock-based compensation under its Amended and Restated 2008 Long Term Performance Plan (2008 LTPP). Awards under the 2008 LTPP may be granted to any officer or employee of the Company or any of its subsidiaries, non-employee directors, or to any other individual who provides services to or on behalf of the Company or any of its subsidiaries. To date, awards under the 2008 LTPP have been in the form of L3’s restricted stock units, performance units and options to purchase L3’s common stock.

On May 3, 2016, the stockholders of L3 approved an amendment to the 2008 LTPP to increase the number of shares authorized for issuance by 6.8 million shares to approximately 26.0 million shares. Each share of L3’s common stock issued under a full value award (that is, awards other than stock options and stock appreciation rights) granted on or after February 23, 2016 is counted as 4.26 shares for purposes of this share limit. Each share issued under full value awards granted between February 26, 2013 and February 22, 2016 is counted as 3.69 shares for purposes of the share limit. At December 31, 2017, $7.9 million shares of L3’s common stock remained available for future awards under the 2008 LTPP.

The Company’s stock-based compensation expense by form of award, including stock-based compensation recorded in discontinued operations related to Vertex Aerospace and NSS, is presented in the table below.



	Year Ended December 31,
	2017			2016			2015
	(in millions)
Stock options	$	7		$	10		$	9
Restricted stock units	43			35			38
Performance units	7			4			2
Total before income taxes	57			49			49
Income taxes	(12		)	(18		)	(18		)
Total after income taxes	45			31			31
Less: Stock-based compensation recorded in discontinued operations, net of income taxes	1			1			1
Stock-based compensation recorded in continuing operations, net of income taxes	$	44		$	30		$	30

Stock Options. The exercise price of stock options granted under the 2008 LTPP may not be less than the fair market value of L3’s common stock on the date of grant. Options expire 10 years after the date of grant and vest ratably over a three year period on the annual anniversary of the date of grant. The options granted to the Company’s Chairman are also subject to performance-based vesting conditions. All unvested options are subject to forfeiture upon termination of employment (subject to customary exceptions for death or disability). All of the stock option awards issued under the 2008 LTPP are non-qualified stock options for U.S. income tax regulations. The table below presents a summary of the Company’s stock option activity at December 31, 2017 and changes during the year then ended.



	Number of Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
	(in thousands)				(in years)	(in millions)
Number of shares under option:
Outstanding at January 1, 2017	2,847.5		$	99.54	6.1	$150
Options granted	470.5		174.53
Options exercised	(521.3	)	90.13
Options forfeited	(97.8	)	120.59
Outstanding at December 31, 2017	2,698.9		$	113.67	5.7	$227
Vested and expected to vest at December 31, 2017⁽¹⁾	2,582.5		$	110.21	5.5	$226
Exercisable at December 31, 2017	1,762.4		$	95.80	4.5	$180

__________________


⁽¹⁾	Represents outstanding options reduced by expected forfeitures for options not fully vested.

The weighted average grant date fair value of the stock options awarded during 2017, 2016 and 2015 was $28.35, $15.90 and $19.76, respectively. The aggregate intrinsic value, disclosed in the table above, represents the difference between L3’s closing stock price on the last trading day for the period, and the exercise price, multiplied by the number of in-the-money stock options.

The total intrinsic value of stock options exercised, based on the difference between the L3’s stock price at the time of exercise and the related exercise price, was $44 million, $34 million and $35 million for the years ended December 31, 2017, 2016 and 2015, respectively. At December 31, 2017, unrecognized compensation cost related to stock options was $7 million ($6 million after income taxes), which is expected to be recognized over a weighted average remaining period of 1.3 years.

The actual income tax benefit realized related to compensation deductions arising from the exercise of stock options by the Company’s employees totaled $16 million, $12 million and $13 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Stock Option Fair Value Estimation Assumptions. The Company estimates the fair value of its stock options at the date of grant using the Black-Scholes option-pricing valuation model. The Company’s valuation model is affected by L3’s stock price as well as weighted average assumptions for a number of subjective variables described below.


•	Expected Holding Period. The expected holding period represents the period of time that granted stock options are expected to be outstanding until they are exercised. The Company uses historical stock option exercise data to estimate the expected holding period.


•	Expected Volatility. Expected volatility is based on L3’s historical share price volatility matching the expected holding period.


•	Expected Dividend Yield. Expected dividend yield is based on L3’s anticipated dividend payments and historical pattern of dividend increases over the expected holding period.


•	Risk-Free Interest Rates. The risk-free interest rates for stock options are based on U.S. Treasuries for a maturity period matching the expected holding period.

Changes in assumptions can materially impact the estimated fair value of stock options. The weighted average assumptions used in the valuation model are presented in the table below.



	2017 Grants		2016 Grants		2015 Grants
Expected holding period (in years)	5.2		5.0		5.0
Expected volatility	19.9	%	21.3	%	21.4	%
Expected dividend yield	2.0	%	2.8	%	2.4	%
Risk-free interest rate	2.0	%	1.1	%	1.5	%

Restricted Stock Units. The Company awards restricted stock units that automatically convert into shares of L3’s common stock upon vesting (in the case of awards granted to employees) or upon the date on which the recipient ceases to be a director (in the case of awards granted to directors). Restricted stock units typically vest three years after the grant date for employees and one year after the grant date for non-employee directors, or if earlier, on the date of the first annual stockholders meeting held after the grant date. The restricted stock units automatically convert into shares of L3’s common stock upon vesting. The weighted average grant date fair value of the restricted stock units awarded during 2017, 2016 and 2015 was $169.23, $116.72 and $128.59, respectively. The grant date fair value of the restricted stock unit awards is based on L3’s closing stock price at the date of grant and is generally recognized as compensation expense on a straight-line basis over the vesting period. However, for employees who attain retirement eligibility status prior to the end of the three-year cliff vesting period and who have provided at least one year of service after the date of grant, compensation expense is recognized over the shorter period from the date of grant to the retirement eligibility date. For grants of restricted stock units made during the year ended December 31, 2017, retirement eligible employees are those employees that either: (1) have attained the age of 60 and completed at least five years of service (which service must be continuous through the date of termination except for a single break in service that does not exceed one year in length) or (2) have attained the age of 65 (without regard to their length of service at L3).

The table below presents a summary of the Company’s nonvested restricted stock unit awards at December 31, 2017 and changes during the year then ended.



	Number of Shares		Weighted Average Grant Date Fair Value
	(in thousands)
Nonvested balance at January 1, 2017	977.9		$	119.55
Granted	305.6		169.23
Vested	(318.4	)	114.46
Forfeited	(62.4	)	134.56
Nonvested balance at December 31, 2017	902.7		$	137.12

At December 31, 2017, total unrecognized compensation costs related to nonvested restricted stock unit awards were $34 million ($26 million after income taxes) and are expected to be recognized over a weighted average remaining period of 1.1 years. The total fair value of restricted stock unit awards vested during the years ended December 31, 2017, 2016 and 2015 as of their vesting dates was $53 million, $57 million and $82 million, respectively.

Performance Units. The Company grants performance unit awards, with each unit having a value at the time of grant equal to a share of L3’s common stock. The number of units ultimately earned can range from zero to 200% of the original award based upon the level of performance achieved by the Company over the associated performance period in relation to pre-determined performance goals. Units earned under the program are converted into shares of L3’s common stock, or are paid in cash based on the closing price of L3’s common stock at the end of the performance period, as determined at the time of grant by the Compensation Committee of the Board of Directors.

During the years ended December 31, 2017, 2016, and 2015, the Company granted performance unit awards with a weighted average grant date fair value per unit of $168.80, $116.20 and $129.03, respectively. All the awards granted in 2017, 2016, and 2015 have performance conditions based on L3’s diluted EPS. The performance periods for the awards began on January 1 of the applicable grant year and end on December 31 of the year corresponding to a three-year performance period. Units earned under the awards are convertible into shares of L3’s common stock. At December 31, 2017, total unrecognized compensation costs related to the awards were $5 million ($5 million after income taxes) and are expected to be recognized over a weighted average remaining period of 1.7 years.

The table below presents a summary of the Company’s performance unit awards based on expected performance at December 31, 2017 and changes during the year then ended.



	Payable in Shares (EPS)
	Number of Units		Weighted Average Grant Date Fair Value
	(in thousands)
Outstanding at January 1, 2017	124.7		$	120.83
Granted	33.9		168.80
Increase due to expected performance	29.7		146.89
Vested	(48.4	)	129.03
Forfeited	(7.8	)	121.06
Outstanding at December 31, 2017	132.1		$	135.99

The performance period for awards granted in 2015 ended on December 31, 2017. Based on L3’s cumulative diluted EPS during the performance period, a total of 48,365 performance units having a fair market value of $10 million as of their vesting date were earned by the participants on December 31, 2017.

Employee Stock Purchase Plan. Effective July 1, 2009, the Company adopted the 2009 Employee Stock Purchase Plan (2009 ESPP). Under the 2009 ESPP, eligible employees are offered options to purchase shares of L3’s common stock at the end of each six-month offering period at 95% of fair market value based on the average of the highest and lowest sales prices for the stock on the purchase date. Eligible employees generally include all employees of the Company and each subsidiary or affiliate of the Company that has been designated to participate in the 2009 ESPP. Offering periods begin on the first trading day in January and July of each calendar year and end on the last trading day in June and December of each calendar year. Share purchases are funded through payroll deductions of up to 10% of an employee’s eligible compensation for each payroll period, or $21,250 each calendar year.

At December 31, 2017, 3.5 million shares were available for future issuance under the 2009 ESPP (i.e., excluding the effect of shares issued in January 2018 as described below). In July 2017, the Company issued 0.1 million shares under the 2009 ESPP at an average price of $158.59 per share, which covered employee contributions for the six months ended June 30, 2017. In January 2018, the Company issued 0.1 million shares under the 2009 ESPP at an average price of $188.72 per share, which covered employee contributions for the six months ended December 31, 2017. The 5% discount is not recognized as compensation expense in accordance with the accounting standard for share-based compensation expense.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

. Commitments and Contingencies

Non-Cancelable Operating Leases

The Company leases certain facilities and equipment under agreements expiring at various dates through 2046. Certain leases contain renewal options or escalation clauses providing for increased rental payments based upon maintenance, utility and tax increases. No lease agreement imposes a restriction on the Company’s ability to pay dividends, engage in debt or equity financing transactions, or enter into further lease agreements.

The following table presents future minimum payments under non-cancelable operating leases with initial or remaining terms in excess of one year at December 31, 2017.



	Real Estate			Equipment		Total
	(in millions)
2018	$	101		$	5	$	106
2019	81			3		84
2020	106			2		108
2021	60			—		60
2022	57			—		57
Thereafter	236			—		236
Total minimum payments required	641			10		651
Sublease rentals under non-cancelable leases	(9		)	—		(9		)
Net minimum payments required	$	632		$	10	$	642

Rent expense was $103 million for 2017, $97 million for 2016, and $102 million for 2015. Sublease rental income was $1 million for 2017, and $2 million for each of 2016 and 2015, respectively.

Letters of Credit

The Company enters into standby letters of credit with financial institutions covering performance and financial guarantees pursuant to contractual arrangements with certain customers. The Company had total outstanding letters of credit aggregating to $416 million and $402 million at December 31, 2017 and 2016, respectively. The Company had the full availability of its $1 billion Credit Facility at December 31, 2017. These letters of credit may be drawn upon in the event of the Company’s nonperformance.

Guarantees

The Company, from time to time, enters into contractual guarantees that arise in connection with its business acquisitions, dispositions, and other contractual arrangements in the normal course of business.

In connection with the spin-off of Engility in 2012, L3 entered into a Distribution Agreement and several other agreements that govern certain aspects of L3’s relationship with Engility, including employee matters, tax matters, transition services, and the future supplier/customer relationship between L3 and Engility. These agreements generally provide cross-indemnities that, except as otherwise provided, are principally designed to place the financial responsibility for the obligations and liabilities of each entity with that respective entity. Engility has joint and several liability with L3 to the U.S. IRS for the consolidated U.S. Federal income taxes of L3’s consolidated group for taxable periods in which Engility was a part of that group. However, the Tax Matters Agreement specifies the portion of this tax liability for which L3 and Engility will each bear responsibility, and L3 and Engility have agreed to indemnify each other against any amounts for which the other is not responsible. The Tax Matters Agreement also allocates responsibility between L3 and Engility for other taxes, including special rules for allocating tax liabilities in the event that the spin-off is determined not to be tax-free. Though valid as between the parties, the Tax Matters Agreement is not binding on the IRS.

The Company has three existing real estate lease agreements, which include residual guarantee amounts, expiring on August 31, 2020 and are accounted for as operating leases. On or before the lease expiration date, the Company can exercise options under the lease agreements to renew the leases, purchase the properties for $45 million, or sell the properties on behalf of the lessor (the “Sale Option”). If the Company elects the Sale Option, the Company must pay the lessor a residual guarantee amount of $39 million for the properties, on or before the lease expiration date. In addition, at the time the properties are sold, the Company must pay the lessor a supplemental rent payment equal to the gross sales proceeds in excess of the residual guarantee, provided that such amount shall not exceed $6 million. For these real estate lease agreements, if the gross sales proceeds are less than the sum of the residual guarantee amount and the supplemental rent payment, the Company is required to pay a supplemental rent payment to the extent the reduction in the fair value of the properties is demonstrated by an independent appraisal to have been caused by the Company’s failure to properly maintain the properties. The aggregate residual guarantee amounts equal $39 million and are included in the future minimum payments under non-cancelable real estate operating lease payments relating to the expiration dates of such leases.

The Company has a contract to provide and operate a full-service training facility for the USAF, including simulator systems adjacent to a USAF base in Oklahoma. The Company acted as the construction agent on behalf of the third-party owner-lessors for procurement and construction for the simulator systems, which were completed and delivered in August 2002. The Company, as lessee, entered into operating lease agreements for a term of 15 years for the simulator systems with the owner-lessors. During the first quarter of 2018, the Company expects to purchase the simulator systems at the end of their respective lease terms for approximately $15 million.

Environmental Matters

Management continually assesses the Company’s obligations with respect to applicable environmental protection laws, including those obligations assumed in connection with certain business acquisitions. While it is difficult to determine the timing and ultimate cost to be incurred by the Company in order to comply with these laws, based upon available internal and external assessments, with respect to those environmental loss contingencies of which management is aware, the Company believes that there are no environmental loss contingencies that, individually or in the aggregate, would be material to the Company’s consolidated results of operations. The Company accrues for these contingencies when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated.

Procurement Regulations

A substantial majority of the Company’s revenues are generated from providing products and services under legally binding agreements or contracts with the U.S. Government, foreign government customers and state and local governments. U.S. Government contracts are subject to extensive legal and regulatory requirements, and, from time to time, agencies of the U.S. Government investigate whether such contracts were and are being conducted in accordance with these requirements. The Company is currently cooperating with the U.S. Government on several investigations from which civil, criminal or administrative proceedings have or could result and give rise to fines, penalties, compensatory and treble damages, restitution and/or forfeitures, including investigations into the pricing of certain contracts entered into by the C&NS segment. The Company does not currently anticipate that any of these investigations will have a material adverse effect, individually or in the aggregate, on its consolidated financial position, results of operations or cash flows. However, under U.S. Government regulations, an indictment of the Company by a federal grand jury, or an administrative finding against the Company as to its present responsibility to be a U.S. Government contractor or subcontractor, could result in the Company being suspended for a period of time from eligibility for awards of new government contracts or task orders or in a loss of export privileges. A conviction, or an administrative finding against the Company that satisfies the requisite level of seriousness, could result in debarment from contracting with the federal government for a specified term. In addition, all of the Company’s U.S. Government contracts: (1) are subject to audit and various pricing and cost controls, (2) include standard provisions for termination for the convenience of the U.S. Government or for default and (3) are subject to cancellation if funds for contracts become unavailable. Foreign government contracts generally include comparable provisions relating to terminations for convenience or default, as well as other procurement clauses relevant to the foreign government.

Litigation Matters

The Company is also subject to litigation, proceedings, claims or assessments and various contingent liabilities incidental to its businesses, including those specified below. Furthermore, in connection with certain business acquisitions, the Company has assumed some or all claims against, and liabilities of, such acquired businesses, including both asserted and unasserted claims and liabilities.

In accordance with the accounting standard for contingencies, the Company records a liability when management believes that it is both probable that a liability has been incurred and the Company can reasonably estimate the amount of the loss. Generally, the loss is recorded at the amount the Company expects to resolve the liability. The estimated amounts of liabilities recorded for pending and threatened litigation are disclosed in Note 7. Amounts recoverable from insurance contracts or third parties are recorded as assets when recovery is deemed probable. At December 31, 2017, the Company did not record any amounts for recoveries from insurance contracts or third parties in connection with the amount of liabilities recorded for pending and threatened litigation. Legal defense costs are expensed as incurred. The Company believes it has recorded adequate provisions for its litigation matters. The Company reviews these provisions to reflect the impact of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular matter. While it is reasonably possible that an unfavorable outcome may occur in one or more of the following matters, unless otherwise stated below, the Company believes that it is not probable that a loss has been incurred in any of these matters. With respect to the litigation matters below for which it is reasonably possible that an unfavorable outcome may occur, an estimate of loss or range of loss is disclosed when such amount or amounts can be reasonably estimated. Although the Company believes that it has valid defenses with respect to legal matters and investigations pending against it, the results of litigation can be difficult to predict, particularly those involving jury trials. Therefore, it is possible that one or more of the following or other contingencies could have a material impact on the financial position, results of operations or cash flows of the Company in future periods.

Derivative Action. On July 13, 2016, a shareholder derivative complaint was filed in the Supreme Court of New York, County of New York, against certain of the Company’s current and former directors and officers. The complaint alleged, among other things, that the defendants breached fiduciary duties, caused corporate waste and were unjustly enriched in connection with misconduct and accounting errors identified by the Company at its ISRS segment, and sought monetary damages, pre- and post-judgment interest, equitable relief and fees and expenses on behalf of the Company. However, the complaint was never served on any defendant, and the Company believes it has been abandoned.

HVC Alkmaar. On July 23, 2014, a notice of claim was received by the Company’s former JovyAtlas business unit. The notice relates to losses resulting from a fire that occurred at an HVC Alkmaar bio-energy plant on July 21, 2013. The notice states that the fire resulted from the failure of an uninterruptible power supply (UPS) to provide sufficient power to act as a back-up energy supply, alleges that JovyAtlas was the manufacturer and service provider for the UPS and claims €11 million in estimated property damages and €35 million in estimated business interruption damages. The Company has tendered the notice of claim to its insurance carriers.

Pension and Other Postretirement Benefits

12 Months Ended

Dec. 31, 2017

Retirement Benefits [Abstract]

Pension and Other Postretirement Benefits

. Pension and Other Postretirement Benefits

The following table summarizes changes in the benefit obligations, the plan assets and funded status for all of the Company’s pension and postretirement benefit plans, as well as the aggregate balance sheet impact.



	Pension Plans						Postretirement Benefit Plans
	2017			2016			2017			2016
	(in millions)
Change in benefit obligation:
Benefit obligation at the beginning of the year	$	3,758		$	3,448		$	177		$	184
Service cost	97			94			2			2
Interest cost	142			135			5			6
Plan participants’ contributions	2			2			5			4
Amendments	—			15			—			(3		)
Actuarial loss (gain)	391			181			(13		)	(3		)
Foreign currency exchange rate changes	22			9			2			—
Curtailments and special termination benefits	2			2			—			—
Benefits paid	(186		)	(128		)	(13		)	(13		)
Benefit obligation at the end of the year	$	4,228		$	3,758		$	165		$	177
Change in plan assets:
Fair value of plan assets at the beginning of the year	$	2,721		$	2,552		$	60		$	57
Actual return on plan assets	391			189			8			5
Employer contributions	97			97			7			7
Plan participants’ contributions	2			2			5			4
Foreign currency exchange rate changes	22			9			—			—
Benefits paid	(186		)	(128		)	(13		)	(13		)
Fair value of plan assets at the end of the year	$	3,047		$	2,721		$	67		$	60
Unfunded status at the end of the year	$	(1,181	)	$	(1,037	)	$	(98	)	$	(117	)

Assets and (liabilities) recognized on the consolidated balance sheets consist of:
Non-current assets	$	48		$	37		$	—		$	—
Current liabilities	(6		)	(6		)	(8		)	(8		)
Non-current liabilities	(1,223		)	(1,068		)	(90		)	(109		)
	$	(1,181	)	$	(1,037	)	$	(98	)	$	(117	)

The table below summarizes the net loss and prior service cost balances at December 31, in the accumulated other comprehensive loss account, before related tax effects, for all of the Company’s pension and postretirement benefit plans.



	Pension Plans				Postretirement Benefit Plans
	2017		2016		2017			2016
	(in millions)
Net loss (gain)	$	1,035	$	896	$	(3	)	$	(12	)
Prior service cost (credit)	10		14		(27		)	(4		)
Total amount recognized	$	1,045	$	910	$	(30	)	$	(16	)

The aggregate accumulated benefit obligation (ABO) for all of the Company’s pension plans was $3,831 million at December 31, 2017 and $3,413 million at December 31, 2016. The table below presents information for the pension plans with an ABO in excess of the fair value of plan assets at December 31, 2017 and 2016.



	Pension Plans
	2017		2016
	(in millions)
Projected benefit obligation	$	3,875	$	3,528
Accumulated benefit obligation	$	3,490	$	3,192
Fair value of plan assets	$	2,651	$	2,456

The table below summarizes the weighted average assumptions used to determine the benefit obligations for the Company’s pension and postretirement plans disclosed at December 31, 2017 and 2016.



	Pension Plans						Postretirement Benefit Plans
	2017			2016			2017			2016
Benefit obligations:
Discount rate	3.78	%	⁽¹⁾	4.40	%	⁽¹⁾	3.59	%	⁽²⁾	4.05	%	⁽²⁾
Rate of compensation increase	3.50	%	⁽³⁾	3.50	%	⁽³⁾

__________________


⁽¹⁾	The weighted average discount rate assumptions used at December 31, 2017 and 2016 were comprised of separate assumptions determined by country of 3.81% and 4.45% for the U.S. based plans, respectively, and 3.39% and 3.79% for the Canadian based plans, respectively.


⁽²⁾	The weighted average discount rate assumptions used at December 31, 2017 and 2016 were comprised of separate assumptions determined by country of 3.63% and 4.11% for the U.S. based plans, respectively, and 3.33% and 3.64% for the Canadian based plans, respectively.


⁽³⁾	The weighted average rate of compensation increase assumptions were comprised of separate assumptions determined by country of 3.5% for both the U.S. based plans and Canadian based plans at December 31, 2017 and 2016.

The following table summarizes the components of net periodic benefit cost for the Company’s pension and postretirement benefit plans for the years ended December 31, 2017, 2016 and 2015.



	Pension Plans									Postretirement Benefit Plans
	2017			2016			2015			2017			2016			2015
	(in millions)
Components of net periodic benefit cost:
Service cost ⁽¹⁾	$	97		$	94		$	112		$	2		$	2		$	3
Interest cost	142			135			149			5			6			7
Expected return on plan assets ⁽¹⁾	(197		)	(186		)	(194		)	(4		)	(4		)	(5		)
Amortization of prior service cost (credits)	1			—			1			(1		)	(2		)	(2		)
Amortization of net loss (gains)	61			52			68			(2		)	(2		)	—
Curtailment loss and special termination benefits ⁽²⁾	6			2			3			—			—			—
Net periodic benefit cost	$	110		$	97		$	139		$	—		$	—		$	3

__________________

⁽¹⁾

In connection with the adoption of ASU 2017-07, the Company reclassified pension plan administrative expenses amounting to $15 million, $14 million and $11 million for the years ended December 31, 2017, 2016 and 2015, respectively, from the service cost component to the expected return on plan assets component of net periodic benefit cost. Taking into account the aforementioned policy change in connection with the adoption of this standard, operating income included in the Company’s Statements of Operations increased by $11 million, $1 million, and $27 million for the years ended December 31, 2017, 2016, and 2015, respectively, with a corresponding decrease of Interest and other income, net. The Company’s percentage assumptions for expected long-term return on plan assets, which are disclosed further below, exclude expected plan administrative expenses.


⁽²⁾	During the year ended December 31, 2017, the curtailment loss and special termination benefits charge is primarily due to a pension curtailment charge in connection with the decision to discontinue future service accruals for substantially all salaried employee defined benefit plans effective January 1, 2019.

In 2016, the Company changed the approach used to measure the service and interest components of expense for all of its pension and postretirement benefit plans. For fiscal 2015 and previous periods, the Company measured the service and interest cost components using a single weighted-average discount rate derived from the yield curve used to measure the benefit obligations at the beginning of the period. Beginning in fiscal 2016, the Company elected to use a spot rate approach for its plans in the measurement of the components of benefit cost by applying specific spot rates along that yield curve to the relevant projected cash flows, as the Company believes the new approach provides a more precise measurement of service and interest costs. This change does not affect the measurement of the Company’s total benefit obligation. The Company has accounted for this change prospectively as a change in accounting estimate.

The following table summarizes the other changes in plan assets and benefit obligations recognized in other comprehensive income for the Company’s pension and postretirement benefit plans for the years ended December 31, 2017, 2016 and 2015.



	Pension Plans									Postretirement Benefit Plans
	2017			2016			2015			2017			2016			2015
	(in millions)
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss):
Net loss (gain)	$	200		$	179		$	(132	)	$	(17	)	$	(4	)	$	(7	)
Prior service (cost) credit	(4		)	15			—			—			(2		)	—
Amortization of net (loss) gain	(61		)	(52		)	(68		)	2			2			—
Amortization of prior service (cost) credit	(1		)	—			(1		)	1			2			2
Total recognized in other comprehensive income (loss)	134			142			(201		)	(14		)	(2		)	(5		)
Total recognized in net periodic benefit cost and other comprehensive income (loss)	$	244		$	239		$	(62	)	$	(14	)	$	(2	)	$	(2	)

The following table summarizes the amounts expected to be amortized from accumulated OCI and recognized as components of net periodic benefit costs during 2018.



	Pension Plans		Postretirement Benefit Plans			Total
	(in millions)
Net loss (gain)	$	74	$	(3	)	$	71
Prior service credit	—		(1		)	(1		)
	$	74	$	(4	)	$	70

The table below summarizes the weighted average assumptions used to determine the net periodic benefit cost for the years ended December 31, 2017, 2016 and 2015.



	Pension Plans									Postretirement Benefit Plans
	2017			2016			2015			2017			2016			2015
Discount rates:
Benefit obligation	4.40	%	⁽¹⁾	4.67	%	⁽¹⁾	4.14	%	⁽¹⁾	4.05	%	⁽⁴⁾	4.22	%	⁽⁴⁾	3.70	%	⁽⁴⁾
Service cost	4.55	%		4.83	%		—	%	⁽⁵⁾	4.21	%		4.37	%		—	%	⁽⁵⁾
Interest cost	3.84	%		3.95	%		—	%	⁽⁵⁾	3.26	%		3.26	%		—	%	⁽⁵⁾
Expected long-term return on plan assets	7.92	%	⁽²⁾	7.92	%	⁽²⁾	8.14	%	⁽²⁾	7.43	%		7.42	%		7.65	%
Rate of compensation increase	3.50	%	⁽³⁾	3.50	%	⁽³⁾	3.50	%	⁽³⁾

__________________


⁽¹⁾	The weighted average discount rate assumptions used for the years ended December 31, 2017, 2016, and 2015 were comprised of separate assumptions determined by country of 4.45%, 4.73% and 4.20% for the U.S. based plans and 3.79%, 3.93% and 3.90% for the Canadian based plans, respectively.


⁽²⁾	The weighted average expected long-term return on plan assets assumptions used were comprised of separate assumptions determined by country of 8.00% for each of the years ended December 31, 2017 and 2016 and 8.25% for the year ended December 31, 2015 for the U.S. based plans and 7.25% for the Canadian based plans for the years ended December 31, 2017, 2016 and 2015.


⁽³⁾	The weighted average rate of compensation increase assumptions used for the years ended December 31, 2017, 2016 and 2015 were comprised of separate assumptions determined by country of 3.50% for both the U.S and Canadian based plans.


⁽⁴⁾	The weighted average discount rate assumptions used for the years ended December 31, 2017, 2016 and 2015 were comprised of separate assumptions determined by country of 4.11%, 4.28% and 3.70% for the U.S. based plans and 3.64%, 3.74% and 3.70% for the Canadian based plans, respectively.


⁽⁵⁾	Not applicable as the Company changed to the spot rate approach beginning in 2016 as described above.

The expected long-term return on plan assets assumption represents the average rate that the Company expects to earn over the long-term on the assets of the Company’s benefit plans, including those from dividends, interest income and capital appreciation, net of investment management expenses. The Company utilizes a third-party consultant to assist in the development of the expected long-term return on plan assets, which is based on expectations regarding future long-term rates of return for the plans’ investment portfolio, with consideration given to the allocation of investments by asset class and historical rates of return for each individual asset class. The Company utilizes a building block methodology that utilizes historical and forward looking rates of return for each asset class and takes into account expected returns above inflation and risk premium. These long-term rates of return are then applied to the target portfolio allocations that are generally aligned with the actual asset allocations of the Company’s plans to develop the expected long-term rate of return.

The annual increase in cost of benefits (health care cost trend rate) for the Company’s U.S. based plans covering retirees under 65 years of age is assumed to be an average of 6.5% in 2018 and is assumed to gradually decrease to a rate of 5.0% in 2021 and thereafter. The health care cost trend rate for the Company’s U.S. based plans covering retirees over 65 years of age is assumed to be an average of 8.0% in 2018 and is assumed to gradually decrease to a rate of 5.0% in 2024 and thereafter. The health care cost trend rate for the Company’s Canadian based plans is assumed to be an average of 6.25% in 2018 and is assumed to gradually decrease to a rate of 5.0% in 2023 and thereafter. Health care cost trend assumptions are based on (1) observed or expected short term rates of increase for different types of health models based on actual claims experience and benchmarking, and (2) a reasonable estimate of an appropriate, sustainable level of health care cost trend in the future, weighting the factors that primarily influence trends, which are price inflation and cost leveraging benefit plan features. Assumed health care cost trend rates can have a significant effect on amounts reported for postretirement medical benefit plans. A one percentage point change in the assumed health care cost trend rates would have the following effects:



	1 percentage point
	Increase		Decrease
	(in millions)
Effect on total service and interest cost	$	—	$	—
Effect on postretirement benefit obligations	$	5	$	(4	)

Plan Assets. The Company’s Benefit Plan Committee (Committee) has the responsibility to formulate the investment policies and strategies for the plans’ assets. The Committee structures the investment of plan assets to achieve the following goals: (1) maximize the plans’ long-term rate of return on assets for an acceptable level of risk; and (2) limit the volatility of investment returns and consequent impact on the plans’ assets. In the pursuit of these goals, the Committee has formulated the following investment policies and objectives: (1) invest assets of the plans in a manner consistent with the fiduciary standards of the Employee Retirement Income Security Act of 1974 (ERISA); (2) preserve the plans’ assets; (3) maintain sufficient liquidity to fund benefit payments and pay plan expenses; (4) evaluate the performance of investment managers; and (5) achieve, on average, a minimum total rate of return equal to the established benchmarks for each asset category.

The Committee retains a professional investment consultant to advise the Committee and help ensure that the above policies and strategies are met. The Committee does not actively manage the day to day operations and selection process of individual securities and investments, as it retains the professional services of qualified investment management organizations to fulfill those tasks. Qualified investment management organizations are evaluated on several criteria for selection, with a focus on the investment management organizations’ demonstrated capability to achieve results that will meet or exceed the investment objectives they have been assigned and conform to the policies established by the Committee. While the investment management organizations have investment discretion over the assets placed under their management, the Committee provides each investment manager with specific investment guidelines relevant to its asset class.

The Committee has established the allowable range that the plans’ assets may be invested in for each major asset category. In addition, the Committee has established guidelines regarding diversification within asset categories to limit risk and exposure to a single or limited number of securities. The investments of the plans’ include a diversified portfolio of both equity and fixed income investments. Equity investments are further diversified across U.S. and non-U.S. stocks, small to large capitalization stocks, and growth and value stocks. Fixed income assets are diversified across U.S. and non-U.S. issuers, corporate and governmental issuers, and credit quality. The plan also invests in real estate through publicly traded real estate securities. Derivatives may be used only for hedging purposes or to create synthetic long positions. The plans are prohibited from directly owning commodities, unregistered securities, restricted stock, private placements, or interests in oil, gas, mineral exploration, or other development programs. Further, short selling or utilizing margin buying for investment purposes is prohibited.

The table below presents the allowable range for each major category of the plans’ assets at December 31, 2017 as well as the Company’s pension plan and postretirement benefit plan weighted-average asset allocations at December 31, 2017 and 2016, by asset category.



	U.S.					Canada
Asset Category	Range	2017		2016		Range	2017		2016
Domestic equity⁽¹⁾	30%-60%	47	%	55	%	—	15	%	15	%
International equity⁽²⁾	10%-20%	11		10		—	47		62
Total equities	45%-75%	58		65		40%-80%	62		77
Fixed income securities	20%-40%	28		22		—	25		13
Other, primarily cash and cash equivalents	0%-15%	7		5		—	13		10
Total fixed income securities and cash and cash equivalents	NA	NA		NA		20%-60%	38		23
Real estate securities	0%-15%	7		8		—	—		—
Total		100	%	100	%		100	%	100	%

__________________


⁽¹⁾	Domestic equities for Canadian plans refers to equities of Canadian companies.


⁽²⁾	International equities for Canadian plans includes equities of U.S. companies.

NA - Not applicable. The Company’s Master Pension Trust Investment Policy does not provide an allocation percentage range to fixed income securities and cash and cash equivalents.

The Committee regularly monitors the investment of the plans’ assets to ensure that the actual investment allocation remains within the established range. The Committee also regularly measures and monitors investment risk through ongoing performance reporting and investment manager reviews. Investment manager reviews include assessing the managers’ performance versus the appropriate benchmark index both in the short and long-term period, performance versus peers, and an examination of the risk the managers assumed in order to achieve rates of return.

The table below presents the fair value of the Company’s pension plans’ assets by asset category segregated by level within the fair value hierarchy, as described below.



	U.S. Pension Plans’ Assets									Canadian Pension Plans’ Assets
	Fair Value Measured At December 31, 2017									Fair Value Measured At December 31, 2017
Asset Category	Level 1		Level 2		Level 3		Total			Level 1		Level 2		Level 3		Total
	(in millions)
Equity securities⁽¹⁾:
U.S. Equity	$	1,297	$	—	$	—	$	1,297		$	71	$	—	$	—	$	71
International Equity	87		—		—		87			105		—		—		105
Fixed Income — Investment Grade⁽²⁾	329		205		—		534			—		—		—		—
Fixed Income — High Yield⁽³⁾	—		219		—		219			—		—		—		—
Real Estate Investment Trusts⁽⁴⁾	196		—		—		196			—		—		—		—
Other⁽⁵⁾	—		198		—		198			8		37		—		45
Total assets at fair value	$	1,909	$	622	$	—	$	2,531		$	184	$	37	$	—	$	221
Liabilities for unsettled trades, net							(30		)							—
Other investments measured at net asset value⁽⁶⁾⁽⁷⁾							203									122
Total							$	2,704								$	343



	U.S. Pension Plans’ Assets									Canadian Pension Plans’ Assets
	Fair Value Measured At December 31, 2016									Fair Value Measured At December 31, 2016
Asset Category	Level 1		Level 2		Level 3		Total			Level 1		Level 2		Level 3		Total
	(in millions)
Equity securities⁽¹⁾:
U.S. Equity	$	1,331	$	—	$	—	$	1,331		$	79	$	—	$	—	$	79
International Equity	85		—		—		85			104		—		—		104
Fixed Income — Investment Grade⁽²⁾	255		159		—		414			—		—		—		—
Fixed Income — High Yield⁽³⁾	—		136		—		136			—		—		—		—
Real Estate Investment Trusts⁽⁴⁾	193		—		—		193			—		—		—		—
Other⁽⁵⁾	—		114		—		114			5		27		—		32
Total assets at fair value	$	1,864	$	409	$	—	$	2,273		$	188	$	27	$	—	$	215
Liabilities for unsettled trades, net							(23		)							—
Other investments measured at net asset value⁽⁶⁾⁽⁷⁾							171									85
Total							$	2,421								$	300

__________________


⁽¹⁾	Equity securities consist of investments in common stock of U.S. and international companies. The fair value of equity securities is based on quoted market prices available in active markets at the close of a trading day, primarily the New York Stock Exchange (NYSE), National Association of Securities Dealers Automated Quotations (NASDAQ), and various international exchanges.

⁽²⁾

Approximately 62% at December 31, 2017 and 2016 of U.S. plan assets that are invested in the Fixed Income — Investment Grade asset category consist of a mutual fund offered by a registered investment company (the Fund) and fixed income securities. The Fund invests in investment grade fixed income securities, mortgaged-backed securities, U.S. treasury and agency bonds and corporate bonds. These investments are classified by the Company as a Level 1 measurement within the fair value hierarchy, as the mutual fund trades on an active market and daily, quoted prices are available. The remaining 38% at December 31, 2017 and 2016 of U.S. plan assets are fixed income securities, primarily investment grade corporate bonds from various industries held directly by the plan. The fair values of these investments are based on yields currently available on comparable bonds of issuers with similar credit ratings, quoted prices of similar bonds in an active market, or cash flows based on observable inputs and are classified as Level 2.


⁽³⁾	Fixed Income — High Yield consists of investments in corporate high-yield bonds from various industries. The fair values of these investments are based on yields currently available on comparable bonds of issuers with similar credit ratings, quoted prices of similar bonds in an active market, or cash flows based on observable inputs.


⁽⁴⁾	Real Estate Investment Trusts (REITs) consist of securities that trade on the major exchanges and invest directly in real estate, either through properties or mortgages.


⁽⁵⁾	Other consists primarily of: (1) money market accounts, which invest primarily in short-term, high quality money market securities such as government obligations, commercial paper, time deposits and certificates of deposit, and are classified as Level 2, and (2) cash, which is classified as Level 1.


⁽⁶⁾	In accordance with ASU 2015-07, certain investments that are measured at fair value using the net asset value (NAV) per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position.

⁽⁷⁾

All of the U.S. plans other investments measured using NAV at December 31, 2017 and 2016 and approximately 31% and 55% at December 31, 2017 and 2016, respectively, of the Canadian plans other investments measured using NAV consist of a regulated commingled equity trust fund, for which fair value is based on the NAV at the end of each month. The NAV is calculated by the fund manager based on the fair value of the fund’s holdings, primarily equity securities traded in active markets, determined as of the end of each month as a practical expedient to estimating fair value. This practical expedient is not used when it is determined to be probable that the fund will sell the investment for an amount different than the reported NAV. Withdrawals are permitted, with notice by the 20th day of each month, based on NAV. Approximately 69% and 45% at December 31, 2017 and 2016, respectively, of the Canadian plans other investments measured using NAV are invested in regulated commingled bond funds (the “Bond Funds”). As these Bond Funds do not trade in an active market, the fair value is based on NAVs calculated by fund managers based on yields currently available on comparable bonds of issuers with similar credit ratings, quoted prices of similar bonds in an active market, or cash flows based on observable inputs as a practical expedient to estimating fair value and classified as Level 2. Withdrawals are permitted monthly, with notice between 0 and 3 days of the transaction date, based on NAV.

The table below presents the fair value of the Company’s postretirement benefit plans’ assets by asset category segregated by level within the fair value hierarchy, as described below.



	Postretirement Benefit Plans’ Assets
	Fair Value Measured At December 31, 2017								Fair Value Measured At December 31, 2016
Asset Category	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
	(in millions)
Equity securities⁽¹⁾:
U.S. Equity	$	38	$	—	$	—	$	38	$	37	$	—	$	—	$	37
International Equity	2		—		—		2		1		—		—		1
Fixed Income — Investment Grade⁽²⁾	10		3		—		13		8		3		—		11
Fixed Income — High Yield⁽³⁾	—		3		—		3		—		2		—		2
Real Estate Investment Trusts⁽⁴⁾	3		—		—		3		3		—		—		3
Other⁽⁵⁾	—		5		—		5		—		3		—		3
Total assets at fair value	$	53	$	11	$	—	$	64	$	49	$	8	$	—	$	57
Other investments measured at net asset value⁽⁶⁾⁽⁷⁾							3								3
Total							$	67							$	60

__________________


⁽¹⁾	Equity securities consist of investments in common stock of U.S. and international companies. The fair value of equity securities is based on quoted market prices available in active markets at the close of a trading day, primarily the NYSE, NASDAQ, and various international exchanges.

⁽²⁾

Approximately 77% and 73% at December 31, 2017 and 2016, respectively, of the postretirement benefit plan assets that are invested in the Fixed Income — Investment Grade asset category consist of the Fund and fixed income securities. The Fund invests in investment grade fixed income securities, mortgaged-backed securities, U.S. treasury and agency bonds and corporate bonds. These investments are classified by the Company as a Level 1 measurement within the fair value hierarchy as the mutual fund trades on an active market and daily, quoted prices are available. The remaining 23% and 27% at December 31, 2017 and 2016, respectively, of the postretirement benefit plan assets are fixed income securities, primarily investment grade corporate bonds from various industries held directly by the plan. The fair values of these investments are based on yields currently available on comparable bonds of issuers with similar credit ratings, quoted prices of similar bonds in an active market, or cash flows based on observable inputs and are classified as Level 2.


⁽³⁾	Fixed Income — High Yield consists of investments in corporate high-yield bonds from various industries. The fair values of these investments are based on yields currently available on comparable bonds of issuers with similar credit ratings, quoted prices of similar bonds in an active market, or cash flows based on observable inputs.


⁽⁴⁾	REITs consist of securities that trade on the major exchanges and invest directly, either through properties or mortgages.


⁽⁵⁾	Other consists primarily of money market accounts, which invest primarily in short-term, high quality money market securities such as government obligations, commercial paper, time deposits and certificates of deposit.


⁽⁶⁾	In accordance with ASU 2015-07, certain investments that are measured at fair value using the NAV per share (or its equivalent)practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position.

⁽⁷⁾

All of the postretirement benefit plans other investments measured using NAV at December 31, 2017 and 2016 consist of a regulated commingled equity trust fund, which fair value is based on NAV at the end of each month. The NAV is calculated by the fund manager based on the fair value of the fund’s holdings, primarily equity securities traded in active markets, determined as of the end of each month as a practical expedient to estimating fair value. This practical expedient is not used when it is determined to be probable that the fund will sell the investment for an amount different than the reported NAV. Withdrawals are permitted, with notice by the 20th day of each month, based on NAV.

Contributions. The funding policy for the Company’s pension and postretirement benefit plans is to contribute at least the minimum required by applicable laws and regulations or to directly make benefit payments where appropriate. The Company makes voluntary, additional contributions to the pension plans depending on a number of factors, including operating cash flow levels, alternative uses for excess cash and the plans’ funded status. At December 31, 2017, all legal funding requirements had been met. For the year ending December 31, 2018, the Company currently expects to contribute approximately $100 million to its pension plans, and approximately $10 million to its postretirement benefit plans.

Estimated Future Benefit Payments. The following table presents expected pension and postretirement benefit payments and expected postretirement subsidies due to the Medicare Prescription Drug Improvement and Modernization Act of 2003, which reflect expected future service, as appropriate.



			Postretirement Benefits
	Pension Benefits		Benefit Payments		Subsidy Receipts
	(in millions)
2018	$	158	$	12	$	—
2019	165		12		—
2020	175		13		—
2021	185		13		—
2022	194		12		—
Years 2023 - 2027	1,128		55		1

Employee Savings Plans. Under its various employee savings plans, the Company matches the contributions of participating employees up to a designated level. The extent of the match, vesting terms and the form of the matching contributions vary among the plans. Under these plans, the Company’s matching contributions in L3’s common stock and cash were $115 million for 2017, $118 million for 2016 and $131 million for 2015. These matching contributions include amounts attributable to discontinued operations of $8 million for 2017, $12 million for 2016 and $24 million for 2015.

Multiemployer Benefit Plans. Certain of the Company’s businesses participate in multiemployer defined benefit pension plans. The Company makes cash contributions to these plans under the terms of collective-bargaining agreements that cover its union employees based on a fixed rate per hour of service worked by the covered employees. The risks of participating in these multiemployer plans are different from single-employer plans in the following aspects: (1) assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers, (2) if a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers and (3) if the Company chooses to stop participating in some of its multiemployer plans, the Company may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability.

Under these plans, the Company contributed cash and recorded expenses for each of its individually significant plans and all of its other plans in aggregate as noted in the table below.



	EIN/Pension Plan Number	Pension Protection Act Zone Status⁽¹⁾		FIP/RP⁽²⁾ Status Pending/ Implemented	Contributions by L3⁽⁷⁾									Surcharge Imposed	Expiration Date of Collective- Bargaining Agreement
Pension Fund	EIN/Pension Plan Number	2017	2016	FIP/RP⁽²⁾ Status Pending/ Implemented	2017			2016			2015			Surcharge Imposed	Expiration Date of Collective- Bargaining Agreement
IAM National Pension Fund	51-6031295/002	Green	Green	No	$	27	⁽³⁾	$	26	⁽⁴⁾	$	23	⁽⁴⁾	No	4/29/2018 to 9/30/2020⁽⁵⁾
Other Pension Funds⁽⁶⁾					—			—			—
Total contributions					$	27		$	26		$	23

__________________


⁽¹⁾	A zone status rating of green indicates the plan is at least 80% funded.


⁽²⁾	Funding improvement plan or rehabilitation plan.


⁽³⁾	At the date the audited financial statements for the Company were issued, the Form 5500 for the plan year ended December 31, 2017 was not available.


⁽⁴⁾	Represents 5% of total plan contributions for the years ended December 31, 2016 and 2015 based on Form 5500.


⁽⁵⁾	The Company is a party to multiple bargaining agreements for multiple projects that require contributions into the IAM National Pension Fund. The most significant of these agreements, expiring April 28, 2019, covers multiple programs in the Company’s ISRS reportable segment and represents 61% of 2017 contributions.


⁽⁶⁾	Consists of three pension funds in which the Company’s contributions are individually, and in the aggregate, insignificant.


⁽⁷⁾	These contributions include amounts attributable to discontinued operations of approximately $26 million for the years ended December 31, 2017 and 2016 and $22 million for the year ended December 31, 2015.

Supplemental Cash Flow Information

12 Months Ended

Dec. 31, 2017

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

. Supplemental Cash Flow Information



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Interest paid	$	165	$	162	$	182
Income tax payments	$	163	$	120	$	130
Income tax refunds	$	16	$	8	$	8

Segment Information

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Segment Information

. Segment Information

In the third quarter of 2018, the Company completed a realignment of its business segments to maximize growth and improve its integration and collaboration across the enterprise. As a result of the realignment, L3 has the following three reportable segments: (1) ISRS, (2) C&NS and (3) Electronic Systems. The consolidated financial statements have been recast for this segment structure.

The Company evaluates the performance of its operating segments and reportable segments based on their sales, operating income and operating margin. Corporate expenses are allocated to the Company’s operating segments using an allocation methodology prescribed by U.S. Government regulations for government contractors. Accordingly, segment results include all costs and expenses, except for goodwill impairment charges, gains or losses related to business divestitures, and certain other items that are excluded by management for purposes of evaluating the operating performance of the Company’s business segments. Certain Corporate and segment expenses of $32 million for 2017 and $29 million for the years ended December 31, 2016 and 2015, that had previously been allocated to the Vertex Aerospace and NSS businesses were retained by the Company and were allocated to L3’s three reportable segments.

The tables below present net sales, operating income, depreciation and amortization, capital expenditures and total assets by reportable segment.



	Year Ended December 31,
	2017			2016			2015
	(in millions)
Net Sales
Products
ISRS	$	2,540		$	2,662		$	2,696
C&NS	2,424			2,238			2,244
Electronic Systems	1,814			1,617			1,716
Elimination of intercompany sales	(45		)	(64		)	(56		)
Total products sales	6,733			6,453			6,600

Services
ISRS	$	1,463		$	1,450		$	1,403
C&NS	717			678			637
Electronic Systems	695			653			612
Elimination of intercompany sales	(35		)	(24		)	(21		)
Total services sales	2,840			2,757			2,631
Consolidated total	$	9,573		$	9,210		$	9,231



	Year Ended December 31,
	2017		2016		2015
	(in millions)

Operating income
ISRS	$	348	$	362	$	312
C&NS	362		298		288
Electronic Systems	321		298		289
Segment total	1,031		958		889
Goodwill impairment charges⁽¹⁾	—		—		(46		)
Loss related to business divestitures⁽²⁾	—		—		(31		)
Consolidated total	$	1,031	$	958	$	812

Depreciation and amortization
ISRS	$	87	$	80	$	83
C&NS	66		63		68
Electronic Systems	72		55		52
Consolidated total	$	225	$	198	$	203

Capital Expenditures
ISRS	$	74	$	83	$	77
C&NS	76		51		48
Electronic Systems	52		66		64
Corporate	22		10		6
Consolidated total	$	224	$	210	$	195

Total Assets
ISRS	$	4,135	$	4,117	$	4,219
C&NS	3,505		3,258		3,222
Electronic Systems	3,939		3,542		3,159
Corporate	709		467		345
Assets held for sale	135		—		—
Assets of discontinued operations	306		481		1,124
Consolidated total	$	12,729	$	11,865	$	12,069

__________________


⁽¹⁾	Represents non-cash goodwill impairment charges recorded during 2015 of $46 million related to a business retained by L3 in connection with the sale of the NSS segment.


⁽²⁾	See Note 3 for information regarding the Company’s business divestitures.

Corporate assets not allocated to the reportable segments primarily include cash and cash equivalents, corporate office fixed assets, and deferred income tax assets.

The table below presents property, plant and equipment, net by geographic area.



	Year Ended December 31,
	2017		2016
	(in millions)
United States	$	936	$	960
All Other	174		147
Total	$	1,110	$	1,107

The Company’s sales attributable to U.S. and international customers, based on location of the customer, are summarized in the table below.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
U.S.	$	7,344	$	6,947	$	6,734
International:
United Kingdom	335		331		336
Canada	280		297		281
Australia	268		254		321
China	167		67		83
South Korea	134		127		207
Japan	125		81		95
France	84		75		62
Other	836		1,031		1,112
Total international	2,229		2,263		2,497
Consolidated	$	9,573	$	9,210	$	9,231

Net sales to principal customers are summarized in the table below.



	Year Ended December 31,
	2017		2016	2015
	(in millions)
U.S. Government agencies⁽¹⁾	$	6,697	6,399	$	6,120
Commercial	1,456		1,280	1,373
Foreign governments⁽¹⁾	1,420		1,531	1,738
Consolidated	$	9,573	9,210	$	9,231

__________________


⁽¹⁾	Includes sales for which the Company is the prime contractor as well as sales based on the ultimate end customer for which the Company is a subcontractor.

Severance and Restructuring Related Costs

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Severance and Restructuring Related Costs

. Severance and Restructuring Related Costs

Consistent with the Company’s strategy to continuously improve its cost structure and right-size its businesses, L3 is completing employment reduction actions across several of its businesses to reduce both direct and indirect costs, including overhead and general and administrative costs. As a result of these initiatives, the Company recorded employee severance and restructuring related costs of $101 million with respect to approximately 1,500 employees during the year ended December 31, 2017, $17 million with respect to approximately 700 employees during the year ended December 31, 2016 and $18 million with respect to approximately 800 employees during the year ended December 31, 2015. Severance and restructuring related costs are reported within cost of sales on the consolidated statements of operations. Severance and restructuring related costs incurred by reportable segment are presented in the table below.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
ISRS⁽¹⁾⁽²⁾	$	38	$	5	$	8
C&NS⁽³⁾	52		8		7
Electronic Systems⁽²⁾	11		4		3
Consolidated	$	101	$	17	$	18

__________________


⁽¹⁾	The severance and restructuring related costs incurred during the year ended December 31, 2017 include a $12 million loss on the sale of a building in Garland, Texas in the fourth quarter of 2017.


⁽²⁾	The severance and restructuring related costs incurred during the year ended December 31, 2017 include $1 million and $5 million of salaried employee pension plan curtailment losses for Electronic Systems and ISRS segments, respectively. See Note 19 for additional information.


⁽³⁾	The severance and restructuring related costs incurred during the year ended December 31, 2017 exclude a pre-tax gain of $42 million on the sale of the Company's property in San Carlos, California in the second quarter of 2017.

The Company had severance and restructuring related liabilities of $23 million and $9 million included in other current liabilities on the Company’s balance sheets at December 31, 2017 and 2016, respectively. The remaining liability balance at December 31, 2017 is expected to be paid in 2018. The table below presents the change to the Company’s severance and restructuring related liability during the year ended December 31, 2017.



	December 31, 2017
	(in millions)
Balance at beginning of period	$	9
Additional provisions	101
Cash payments	(87		)
Balance at end of period	$	23

Unaudited Quarterly Financial Data

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Unaudited Quarterly Financial Data

. Unaudited Quarterly Financial Data

Unaudited summarized financial data by quarter for the years ended December 31, 2017 and 2016 is presented in the table below. The Company’s unaudited quarterly results of operations are affected, significantly in some periods, by the Company’s business acquisitions and divestitures. See Note 3 for additional information.



	First Quarter		Second Quarter		Third Quarter⁽¹⁾		Fourth Quarter⁽²⁾
	(in millions, except per share data)
2017
Sales	$	2,321	$	2,385	$	2,293	$	2,574
Operating income	237		294		232		268
Income from continuing operations	157		195		146		271
Net income	168		207		25		293
Net income attributable to L3	164		202		22		289
Basic EPS from continuing operations⁽³⁾	1.97		2.44		1.83		3.42
Basic EPS⁽³⁾	2.11		2.59		0.28		3.70
Diluted EPS from continuing operations⁽³⁾	1.93		2.39		1.79		3.34
Diluted EPS⁽³⁾	2.07		2.54		0.28		3.62

2016
Sales	$	2,065	$	2,318	$	2,184	$	2,643
Operating income	244		220		211		283
Income from continuing operations	163		134		149		187
Net income	230		151		151		192
Net income attributable to L3	227		147		148		188
Basic EPS from continuing operations⁽³⁾	2.06		1.68		1.89		2.37
Basic EPS⁽³⁾	2.92		1.90		1.91		2.43
Diluted EPS from continuing operations⁽³⁾	2.02		1.66		1.85		2.32
Diluted EPS⁽³⁾	2.87		1.88		1.88		2.38

__________________


⁽¹⁾	The Company recorded a goodwill impairment charge of $187 million or $1.67 per diluted share for the Vertex Aerospace reporting unit in 2017, which is reported in discontinued operations.


⁽²⁾	Provision for income taxes for the fourth quarter of 2017, includes estimated tax benefits of $79 million or $0.99 per diluted share, related to the enactment of U.S. Tax Reform in December 2017.


⁽³⁾	EPS in each quarter is computed using the weighted-average number of shares outstanding during that quarter, while EPS for the full year is computed using the weighted-average number of shares outstanding during the year. Therefore, the sum of the four quarters’ EPS may not equal the full year computed EPS.

Financial Information of L3 and Its Subsidiaries

12 Months Ended

Dec. 31, 2017

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Financial Information of L3 and Its Subsidiaries

The debt of L3, including the Senior Notes and borrowings under amounts drawn against the Credit Facility are guaranteed, on a joint and several, full and unconditional basis, by certain of its domestic subsidiaries (the Guarantor Subsidiaries). See Note 9 for additional information. The foreign subsidiaries and certain domestic subsidiaries of L3 (the Non-Guarantor Subsidiaries) do not guarantee the debt of L3. None of the debt of L3 has been issued by its subsidiaries.

Under the terms of the indentures governing the Senior Notes, the guarantees of the Senior Notes will automatically and unconditionally be released and discharged: (1) upon the release of all guarantees of all other outstanding indebtedness of L3, or (2) upon the determination that such guarantor is no longer a “domestic subsidiary.” In addition, the guarantees of the Senior Notes will be automatically and unconditionally released and discharged in the event of a sale or other disposition of all of the assets of any guarantor, by way of merger, consolidation or otherwise, or a sale of all of the capital stock of such guarantor. There are no restrictions on the payment of dividends from the Guarantor Subsidiaries to L3.

In lieu of providing separate audited financial statements for the Guarantor Subsidiaries, the Company has included the accompanying condensed combining financial statements based on Rule 3-10 of SEC Regulation S-X. The Company does not believe that separate financial statements of the Guarantor Subsidiaries are material to users of the financial statements.

The following condensed combining financial information presents the results of operations, financial position and cash flows of: (1) L3 excluding its consolidated subsidiaries (the Parent), (2) the Guarantor Subsidiaries, (3) the Non-Guarantor Subsidiaries and (4) the eliminations to arrive at the information for L3 on a consolidated basis.



	L3		Guarantor Subsidiaries		Non- Guarantor Subsidiaries		Eliminations			Consolidated L3
	(in millions)
Condensed Combining Balance Sheets:
At December 31, 2017:
Current assets:
Cash and cash equivalents	$	432	$	16	$	285	$	(71	)	$	662
Billed receivables, net	266		244		213		—			723
Contracts in process	706		912		315		—			1,933
Prepaid expenses and other current assets	330		235		124		—			689
Assets held for sale	—		135		—		—			135
Assets of discontinued operations	306		—		—		—			306
Total current assets	2,040		1,542		937		(71		)	4,448
Goodwill	2,099		2,932		1,584		—			6,615
Other assets	658		687		321		—			1,666
Investment in and amounts due from consolidated subsidiaries	5,662		6,310		—		(11,972		)	—
Total assets	$	10,459	$	11,471	$	2,842	$	(12,043	)	$	12,729
Current liabilities	$	811	$	832	$	564	$	(71	)	$	2,136
Liabilities held for sale	—		17		—		—			17
Liabilities of discontinued operations	226		—		—		—			226
Amounts due to consolidated subsidiaries	—		—		391		(391		)	—
Other long-term liabilities	1,009		729		131		—			1,869
Long-term debt	3,330		—		—		—			3,330
Total liabilities	5,376		1,578		1,086		(462		)	7,578
L3 shareholders’ equity	5,083		9,893		1,756		(11,649		)	5,083
Noncontrolling interests	—		—		—		68			68
Total equity	5,083		9,893		1,756		(11,581		)	5,151
Total liabilities and equity	$	10,459	$	11,471	$	2,842	$	(12,043	)	$	12,729



	L3		Guarantor Subsidiaries		Non- Guarantor Subsidiaries		Eliminations			Consolidated L3
	(in millions)
At December 31, 2016:
Current assets:
Cash and cash equivalents	$	262	$	5	$	203	$	(107	)	$	363
Billed receivables, net	261		261		178		—			700
Contracts in process	694		936		228		—			1,858
Prepaid expenses and other current assets	236		145		124		—			505
Assets of discontinued operations	481		—		—		—			481
Total current assets	1,934		1,347		733		(107		)	3,907
Goodwill	2,110		2,785		1,479		—			6,374
Other assets	705		592		287		—			1,584
Investment in and amounts due from consolidated subsidiaries	5,653		5,563		—		(11,216		)	—
Total assets	$	10,402	$	10,287	$	2,499	$	(11,323	)	$	11,865
Current liabilities	$	789	$	833	$	444	$	(107	)	$	1,959
Liabilities of discontinued operations	235		—		—		—			235
Amounts due to consolidated subsidiaries	—		—		832		(832		)	—
Other long-term liabilities	1,500		192		30		—			1,722
Long-term debt	3,325		—		—		—			3,325
Total liabilities	5,849		1,025		1,306		(939		)	7,241
L3 shareholders’ equity	4,553		9,262		1,193		(10,455		)	4,553
Noncontrolling interests	—		—		—		71			71
Total equity	4,553		9,262		1,193		(10,384		)	4,624
Total liabilities and equity	$	10,402	$	10,287	$	2,499	$	(11,323	)	$	11,865



	L3			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated L3
	(in millions)
Condensed Combining Statements of Operations:
For the year ended December 31, 2017:
Total net sales	$	3,520		$	4,852		$	1,581		$	(380	)	$	9,573
Total cost of sales	(3,169		)	(4,446		)	(1,307		)	380			(8,542		)
Operating income	351			406			274			—			1,031
Interest expense	(168		)	—			(1		)	—			(169		)
Interest and other income (loss), net	6			(8		)	11			—			9
Income from continuing operations before income taxes	189			398			284			—			871
Provision for income taxes	(22		)	(47		)	(33		)	—			(102		)
Equity in net income of consolidated subsidiaries	586			144			—			(730		)	—
Income from continuing operations	753			495			251			(730		)	769
Loss from discontinued operations, net of income tax	(76		)	—			—			—			(76		)
Net income	677			495			251			(730		)	693
Net income attributable to noncontrolling interests	—			—			—			(16		)	(16		)
Net income attributable to L3	$	677		$	495		$	251		$	(746	)	$	677
Comprehensive income attributable to L3	$	712		$	604		$	378		$	(982	)	$	712

For the year ended December 31, 2016:
Total net sales	$	3,351		$	4,842		$	1,348		$	(331	)	$	9,210
Total cost of sales	(3,064		)	(4,406		)	(1,113		)	331			(8,252		)
Operating income	287			436			235			—			958
Interest expense	(164		)	—			—			—			(164		)
Interest and other income (loss), net	9			(3		)	11			—			17
Debt retirement charges	(7		)	—			—			—			(7		)
Income from continuing operations before income taxes	125			433			246			—			804
Provision for income taxes	(26		)	(92		)	(53		)	—			(171		)
Equity in net income of consolidated subsidiaries	520			130			—			(650		)	—
Income from continuing operations	619			471			193			(650		)	633
Income from discontinued operations, net of income tax	91			—			—			—			91
Net income	710			471			193			(650		)	724
Net income attributable to noncontrolling interests	—			—			—			(14		)	(14		)
Net income attributable to L3	$	710		$	471		$	193		$	(664	)	$	710
Comprehensive income attributable to L3	$	558		$	409		$	116		$	(525	)	$	558

For the year ended December 31, 2015:
Total net sales	$	3,268		$	4,870		$	1,444		$	(351	)	$	9,231
Total cost of sales	(3,017		)	(4,429		)	(1,247		)	351			(8,342		)
Goodwill impairment charges	—			(26		)	(20		)	—			(46		)
(Loss) gain related to business divestitures	(13		)	(31		)	13			—			(31		)
Operating income	238			384			190			—			812
Interest expense	(161		)	(1		)	—			—			(162		)
Interest and other income (loss), net	3			(15		)	2			—			(10		)
Debt retirement charge	(1		)	—			—			—			(1		)
Income from continuing operations before income taxes	79			368			192			—			639
Provision for income taxes	(16		)	(76		)	(40		)	—			(132		)
Equity in net income of consolidated subsidiaries	429			73			—			(502		)	—
Income from continuing operations	492			365			152			(502		)	507
Loss from discontinued operations, net of income tax	(732		)	—			—			—			(732		)
Net (loss) income	(240		)	365			152			(502		)	(225		)
Net income attributable to noncontrolling interests	—			—			—			(15		)	(15		)
Net (loss) income attributable to L3	$	(240	)	$	365		$	152		$	(517	)	$	(240	)
Comprehensive (loss) income attributable to L3	$	(230	)	$	255		$	41		$	(296	)	$	(230	)



	L3			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated L3
	(in millions)
Condensed Combining Statements of Cash Flows:
For the year ended December 31, 2017:
Operating activities:
Net cash from operating activities from continuing operations	$	374		$	426		$	263		$	(78	)	$	985
Investing activities:
Business acquisitions, net of cash acquired	(316		)	—			—			—			(316		)
Proceeds from sale of businesses, net of closing date cash balances	17			—			1			—			18
Other investing activities	(92		)	(38		)	(25		)	—			(155		)
Net cash used in investing activities from continuing operations	(391		)	(38		)	(24		)	—			(453		)
Financing activities:
Common stock repurchased	(180		)	—			—			—			(180		)
Dividends paid on L3’s common stock	(236		)	—			—			—			(236		)
Other financing activities	490			(377		)	(177		)	114			50
Net cash from (used in) financing activities from continuing operations	74			(377		)	(177		)	114			(366		)
Effect of foreign currency exchange rate changes on cash	—			—			20			—			20
Net increase in cash and cash equivalents of discontinued operations	113			—			—			—			113
Net increase in cash	170			11			82			36			299
Cash and cash equivalents, beginning of the year	262			5			203			(107		)	363
Cash and cash equivalents, end of the year	$	432		$	16		$	285		$	(71	)	$	662



	L3			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated L3
	(in millions)
For the year ended December 31, 2016:
Operating activities:
Net cash from operating activities from continuing operations	$	440		$	509		$	259		$	(186	)	$	1,022
Investing activities:
Business acquisitions, net of cash acquired	(388		)	—			—			—			(388		)
Proceeds from sale of businesses, net of closing date cash cash balances	563			—			(2		)	—			561
Other investing activities	(63		)	(77		)	(43		)	—			(183		)
Net cash from (used in) investing activities from continuing operations	112			(77		)	(45		)	—			(10		)
Financing activities:
Proceeds from sale of senior notes	547			—			—			—			547
Redemption of senior notes	(856		)	—			—			—			(856		)
Common stock repurchased	(373		)	—			—			—			(373		)
Dividends paid on L3’s common stock	(220		)	—			—			—			(220		)
Other financing activities	490			(427		)	(163		)	146			46
Net cash used in financing activities from continuing operations	(412		)	(427		)	(163		)	146			(856		)
Effect of foreign currency exchange rate changes on cash	—			—			(13		)	—			(13		)
Net increase in cash and cash equivalents of discontinued operations	13			—			—			—			13
Net increase in cash	153			5			38			(40		)	156
Cash and cash equivalents, beginning of the year	109			—			165			(67		)	207
Cash and cash equivalents, end of the year	$	262		$	5		$	203		$	(107	)	$	363

For the year ended December 31, 2015:
Operating activities:
Net cash from operating activities from continuing operations	$	633		$	428		$	159		$	(185	)	$	1,035
Investing activities:
Business acquisitions, net of cash acquired	(320		)	—			—			—			(320		)
Proceeds from sale of businesses, net of closing date cash balances	42			—			276			—			318
Other investing activities	(75		)	(78		)	(35		)	—			(188		)
Net cash (used in) from investing activities from continuing operations	(353		)	(78		)	241			—			(190		)
Financing activities:
Repurchases of senior notes	(297		)	—			—			—			(297		)
Common stock repurchased	(740		)	—			—			—			(740		)
Dividends paid on L3's common stock	(214		)	—			—			—			(214		)
Other financing activities	639			(355		)	(418		)	180			46
Net cash used in financing activities from continuing operations	(612		)	(355		)	(418		)	180			(1,205		)
Effect of foreign currency exchange rate changes on cash	—			—			(19		)	—			(19		)
Net increase in cash and cash equivalents of discontinued operations	83			—			—			—			83
Change in cash balance in assets held for sale	—			1			60			—			61
Net (decrease) increase in cash	(249		)	(4		)	23			(5		)	(235		)
Cash and cash equivalents, beginning of the year	358			4			142			(62		)	442
Cash and cash equivalents, end of the year	$	109		$	—		$	165		$	(67	)	$	207

The Company has revised the reported amounts for L3, Guarantor Subsidiaries, Non-Guarantor Subsidiaries and Eliminations in the Condensed Combining Balance Sheets at December 31, 2017 and 2016 and Condensed Combining Statements of Operations for the years ended December 31, 2017, 2016 and 2015, to retrospectively reflect: (a) changes in Guarantor Subsidiaries resulting from the elimination of Vertex Aerospace as a Guarantor Subsidiary due to its sale which occurred on June 29, 2018; (b) additional legal entities included as Guarantor Subsidiaries as the result of the Third Supplemental Indenture dated March 30, 2018; and (c) correction of an error related to the understatement of Equity in net income and Investment in and amounts due from consolidated subsidiaries of certain Guarantor Subsidiaries. As a result of the error discussed in (c) above, Investment in and amounts due from consolidated subsidiaries, Total assets, and Total equity of Guarantor Subsidiaries in the Condensed Combining Balance Sheet was understated by $1,646 million and $1,256 million at December 31, 2017 and 2016, respectively. Additionally, Equity in net income of consolidated subsidiaries and Net income of Guarantor Subsidiaries in the Condensed Combining Statements of Operations for the years ended December 31, 2017, 2016 and 2015 was understated by $144 million, $130 million and $73 million, respectively. The Company assessed the materiality of the error on previously issued financial statements in accordance with SEC Staff Accounting Bulleting No. 99 and No. 108, and concluded that the disclosure error was not material to the Company's previously issued financial statements taken as a whole.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Principles of Consolidation

All references made to financial data noted in the footnotes are to L3’s continuing operations unless otherwise specifically noted.

Accounting Estimates

Revenue Recognition

Research and Development

Product Warranties

The table below presents the changes in the Company’s accrued product warranty costs.



	Year Ended December 31,
	2017			2016
	(in millions)
Accrued product warranty costs⁽¹⁾:
Balance at January 1	$	109		$	105
Acquisitions during this period	3			3
Accruals for product warranties issued during the period	52			51
Foreign currency translation adjustments	1			(1		)
Settlements made during the period	(66		)	(49		)
Balance at December 31	$	99		$	109

__________________


⁽¹⁾	Warranty obligations incurred in connection with long-term production contracts that are accounted for under the POC cost-to-cost method are included within the contract estimates at completion and are excluded from the above amounts. The balances above include both the current and non-current amounts.

Deferred Debt Issue Costs

Pension Plan and Postretirement Benefit Plan Obligations

Stock-Based Compensation

Income Taxes

Cash and Cash Equivalents

Cash and Cash Equivalents: Cash equivalents consist of highly liquid investments with an original maturity of three months or less at the time of purchase.

Contracts in Process

Inventories

Property, Plant and Equipment

Goodwill and Indefinite-lived Intangible Assets

Identifiable Intangible Assets

Derivative Financial Instruments

Derivative Financial Instruments: The Company’s derivative financial instruments include foreign currency forward contracts, which are entered into for risk management purposes.

Treasury Stock

Treasury Stock: The Company records treasury stock purchases at cost, which includes incremental direct transaction costs.

Translation of Foreign Currency and Foreign Currency Transactions

Accounting Standards Issued and Not Yet Implemented

Accounting Standards Implemented

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Changes in Company's Accrued Product Warranty Costs

The table below presents the changes in the Company’s accrued product warranty costs.



	Year Ended December 31,
	2017			2016
	(in millions)
Accrued product warranty costs⁽¹⁾:
Balance at January 1	$	109		$	105
Acquisitions during this period	3			3
Accruals for product warranties issued during the period	52			51
Foreign currency translation adjustments	1			(1		)
Settlements made during the period	(66		)	(49		)
Balance at December 31	$	99		$	109

__________________


⁽¹⁾	Warranty obligations incurred in connection with long-term production contracts that are accounted for under the POC cost-to-cost method are included within the contract estimates at completion and are excluded from the above amounts. The balances above include both the current and non-current amounts.

Acquisitions, Divestitures and Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Net Sales and Income Before Income Taxes for Kigre, G-Air, Doss Aviation, Adaptive Methods, Open Water Power, OceanServer and ETD Business



	Year Ended December 31, 2017
	(in millions)
Net sales	$	80
Loss before income taxes	$	(1	)

Unaudited Pro Forma Statements of Operations Data

The unaudited pro forma Statements of Operations data below include adjustments for additional amortization expense related to acquired intangible assets and depreciation assuming the 2017 and 2016 acquisitions had occurred on January 1, 2016 and January 1, 2015, respectively.



	Year Ended December 31,
	2017		2016
	(in millions, except per share data)
Pro forma net sales	$	9,638	$	9,493
Pro forma income from continuing operations attributable to L3	$	753	$	621
Pro forma net income attributable to L3	$	677	$	712
Pro forma diluted earnings per share from continuing operations	$	9.46	$	7.88
Pro forma diluted earnings per share	$	8.51	$	9.03

Components of Pre-tax (Loss) Gain Recognized, Proceeds Received and Net Sales Included in Continuing Operations From Business Divestitures

The table below presents pre-tax loss recognized, the proceeds received and net sales included in continuing operations from these business divestitures.



	Year Ended December 31, 2015
	Pre-Tax Loss			Proceeds Received		Net Sales
	(in millions)
MSI divestiture	$	(17	)	$	318	$	185
BSI divestiture	(4		)	26		7
Tinsley Product Line divestiture	(8		)	4		9
Klein divestiture	(2		)	10		8
Total	$	(31	)	$	358	$	209

The table below presents pre-tax (loss) gain recognized, the proceeds received and net sales included in continuing operations from these divestitures.



	Year Ended December 31, 2017
	Pre-Tax (Loss) gain			Proceeds Received		Net Sales
	(in millions)
Aviation Jet Services divestiture	$	(5	)	$	1	$	1
Coleman divestiture	(3		)	17		9
Display Product Line divestiture	4			7		—
Total	$	(4	)	$	25	$	10

Net Sales and Income Before Income Taxes for Aviation Jet Services, Coleman, the Display Product Line, MSI, BSI, the Tinsley Product Line and Klein



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Net sales	$	10	$	59	$	259
Income before income taxes	$	2	$	8	$	8

Discontinued Operations, Held-for-sale [Member]

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Major Classes of Assets and Liabilities Included as Discontinued Operations/Held For Sale

The major classes of assets and liabilities included as held for sale related to the Aerostructures businesses are presented in the table below.



	December 31, 2017

Assets
Billed receivables	$	14
Contracts in process	33
Total current assets	47
Property, plant and equipment, net	34
Goodwill	52
Identifiable intangible assets	2
Total assets classified as held for sale	$	135

Liabilities
Accounts payable, trade	$	3
Accrued employment costs	2
Accrued expenses	3
Other current liabilities	5
Total current liabilities	13
Deferred income taxes	4
Total liabilities classified as held for sale	$	17

Vertex Aerospace and NSS [Member]

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Statement of Operations Data Classified as Discontinued Operations



	Year Ended December 31,
	2017			2016			2015
	(in millions)
Net sales	$	1,429		$	1,402		$	2,334
Cost of sales	(1,342		)	(1,357		)	(2,259		)
(Loss) gain related to business divestiture⁽¹⁾	(1		)	64			—
Goodwill impairment charges⁽²⁾	(187		)	—			(909		)
Operating (loss) income from discontinued operations	(101		)	109			(834		)
Interest expense allocated to discontinued operations	(2		)	(5		)	(26		)
(Loss) income from discontinued operations before income taxes	(103		)	104			(860		)
Income tax benefit (expense)	27			(13		)	128
(Loss) income from discontinued operations net of income taxes	$	(76	)	$	91		$	(732	)

__________________


⁽¹⁾	For the year ended December 31, 2017, the Company recognized $1 million of trailing expenses related to the sale of NSS. The year ended December 31, 2016 included a gain of $64 million (before and after income taxes) on the sale of NSS.


⁽²⁾	Due to a decline in estimated fair value, the Company recorded goodwill impairment charges for the years ended December 31, 2016 and 2015. The impairment charge of $187 million recorded during 2017 relates to Vertex Aerospace. The impairment charge of $909 million recorded during 2015 consists of: (i) $571 million related to NSS and (ii) $338 million related to Vertex Aerospace.

Vertex Aerospace [Member]

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Major Classes of Assets and Liabilities Included as Discontinued Operations/Held For Sale



	December 31, 2017		December 31, 2016
	(in millions)
Assets
Current assets	$	284	$	271
Property, plant and equipment, net	13		14
Goodwill	—		187
Other Intangible Assets	7		9
Other assets	2		—
Total assets of discontinued operations	$	306	$	481

Liabilities
Accounts payable, trade	$	63	$	16
Other current liabilities	131		160
Current liabilities	194		176
Long-term liabilities	32		59
Total liabilities of discontinued operations	$	226	$	235

Contracts in Process (Tables)

12 Months Ended

Dec. 31, 2017

Contractors [Abstract]

Components of Contracts in Process



	December 31,
	2017			2016
	(in millions)
Unbilled contract receivables, gross	$	1,874		$	1,890
Unliquidated progress payments	(761		)	(827		)
Unbilled contract receivables, net	1,113			1,063
Inventoried contract costs, gross	891			998
Unliquidated progress payments	(71		)	(203		)
Inventoried contract costs, net	820			795
Total contracts in process	$	1,933		$	1,858

General and Administrative, Independent Research and Development and Bid and Proposal Costs



	Year Ended December 31,
	2017			2016			2015
	(in millions)
Amounts included in inventoried contract costs at beginning of the year	$	173		$	137		$	114
Contract costs incurred:
IRAD and B&P	333			304			280
Other G&A⁽¹⁾	842			749			742
Total	1,175			1,053			1,022
Amounts charged to operating costs and expenses	(1,179		)	(1,017		)	(999		)
Amounts included in inventoried contract costs at end of the year	$	169		$	173		$	137

__________________


⁽¹⁾	Amounts include severance and restructuring related costs of $91 million, $13 million and $14 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Selling, General and Administrative Expenses and Research and Development Expenses



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Selling, general and administrative expenses	$	278	$	223	$	261
Research and development expenses	63		54		52
Total	$	341	$	277	$	313

Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Inventory Disclosure [Abstract]

Inventories at Lower of Cost or Realizable Value

Inventories at Lower of Cost or Realizable Value. The table below presents the components of inventories at the lower of cost (first-in, first-out or average cost) or realizable value.



	December 31,
	2017		2016
	(in millions)
Raw materials, components and sub-assemblies	$	184	$	165
Work in process	98		106
Finished goods	107		59
Total	$	389	$	330

Goodwill and Identifiable Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Changes in Goodwill by Segment

The table below presents the changes in goodwill allocated to the Company’s reporting units in each reportable segment.



	ISRS			C&NS			Electronic Systems			Consolidated Total
	(in millions)
December 31, 2015
Goodwill	$	2,493		$	1,860		$	1,846		$	6,199
Accumulated impairment losses	(46		)	(15		)	(43		)	(104		)
	2,447			1,845			1,803			6,095
Business acquisitions⁽¹⁾	28			20			287			335
Foreign currency translation adjustments	(9		)	3			(50		)	(56		)

December 31, 2016
Goodwill	2,512			1,883			2,083			6,478
Accumulated impairment losses	(46		)	(15		)	(43		)	(104		)
	2,466			1,868			2,040			6,374
Business acquisitions⁽¹⁾	8			73			131			212
Business divestitures⁽²⁾	—			—			(12		)	(12		)
Foreign currency translation adjustments	26			21			46			93
Assets held for sale⁽³⁾	(42		)	—			(10		)	(52		)

December 31, 2017
Goodwill	2,504			1,977			2,238			6,719
Accumulated impairment losses	(46		)	(15		)	(43		)	(104		)
	$	2,458		$	1,962		$	2,195		$	6,615

__________________

⁽¹⁾


⁽²⁾	The decrease for the Electronic Systems segment was due to the divestitures of Coleman and Aviation Jet Services during the quarterly period ended March 31, 2017.


⁽³⁾	The Aerostructures businesses from the Company’s ISRS segment are classified as held for sale as of December 31, 2017.

Identifiable Intangible Assets

The table below presents information for the Company’s identifiable intangible assets that are subject to amortization and indefinite-lived intangible assets.



		December 31, 2017						December 31, 2016
	Weighed Average Amortization Period	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
	(in years)	(in millions)
Customer contractual relationships	14	$	393	$	257	$	136	$	360	$	229	$	131
Technology	10	189		114		75		191		102		89
Other	15	29		14		15		21		12		9
Total subject to amortization		611		385		226		572		343		229
IPR&D	indefinite	66		—		66		—		—		—
Total		$	677	$	385	$	292	$	572	$	343	$	229

Amortization Expense

The table below presents amortization expense recorded by the Company for its identifiable intangible assets.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Amortization expense	$	43	$	33	$	32

Estimated Amortization Expense



	Year Ending December 31,
	2018		2019		2020		2021		2022
	(in millions)
Estimated amortization expense	$	44	$	39	$	31	$	25	$	21

Other Current Liabilities and Other Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Other Liabilities Disclosure [Abstract]

Other Current Liabilities

The table below presents the components of other current liabilities.



	December 31,
	2017		2016
	(in millions)
Other Current Liabilities:
Accrued product warranty costs	$	69	$	68
Estimated costs in excess of estimated contract value to complete contracts in process in a loss position	63		70
Accrued interest	43		43
Deferred revenues	38		34
Estimated contingent purchase price payable for acquired businesses (see Note 3)	11		—
Accruals for pending and threatened litigation	3		14
Other	140		163
Total other current liabilities	$	367	$	392

Other Liabilities

The table below presents the components of other liabilities.



	December 31,
	2017		2016
	(in millions)
Other Liabilities:
Non-current income taxes payable (see Note 16)	$	164	$	121
Deferred compensation	49		47
Accrued product warranty costs	30		41
Accrued workers’ compensation	23		25
Estimated contingent purchase price payable for acquired businesses (see Note 3)	20		29
Notes payable and capital lease obligations	16		10
Other	96		83
Total other liabilities	$	398	$	356

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

The table below presents the components of property, plant and equipment.



	December 31,
	2017			2016
	(in millions)
Land	$	34		$	53
Buildings and improvements	404			437
Machinery, equipment, furniture and fixtures	1,959			1,857
Leasehold improvements	376			337
Gross property, plant and equipment	2,773			2,684
Accumulated depreciation and amortization	(1,663		)	(1,577		)
Property, plant and equipment, net	$	1,110		$	1,107

Debt (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Components of Debt and Reconciliation to Carrying Amount of Current and Long-Term Debt

The components of debt and a reconciliation to the carrying amount of long-term debt is presented in the table below.



	December 31,
	2017			2016
	(in millions)
Borrowings under Revolving Credit Facility⁽¹⁾	$	—		$	—
5.20% Senior Notes due 2019	1,000			1,000
4.75% Senior Notes due 2020	800			800
4.95% Senior Notes due 2021	650			650
3.95% Senior Notes due 2024	350			350
3.85% Senior Notes due 2026	550			550
Principal amount of long-term debt	3,350			3,350
Unamortized discounts	(7		)	(8		)
Deferred debt issue costs	(13		)	(17		)
Carrying amount of long-term debt	$	3,330		$	3,325

__________________


⁽¹⁾	During 2017, L3's aggregate borrowings and repayments under the Credit Facility were $1,328 million. L3 had the full availability of its $1 billion Credit Facility at December 31, 2017 and December 31, 2016

Information Regarding Outstanding Senior Subordinated Notes

The Senior Notes are unsecured senior obligations of L3. The terms of each outstanding Senior Note are presented in the table below.



Note	Date of Issuance		Amount Issued		Discount⁽¹⁾		Net Cash Proceeds		Effective Interest Rate		Redemption at Treasury Rate⁽²⁾⁽³⁾
		(in millions)
5.20% Senior Notes due October 15, 2019	October 2, 2009		$	1,000	$	4	$	987	5.25	%	30 bps
4.75% Senior Notes due July 15, 2020	May 21, 2010		$	800	$	3	$	790	4.79	%	25 bps
4.95% Senior Notes due February 15, 2021	February 7, 2011		$	650	$	4	$	639	5.02	%	25 bps
3.95% Senior Notes due May 28, 2024	May 28, 2014		$	650	$	3	$	641	4.02	%	20 bps
3.85% Senior Notes due December 15, 2026	December 5, 2016		$	550	$	3	$	542	3.91	%	25 bps

__________________


⁽¹⁾	Bond discounts are recorded as a reduction to the principal amount of the notes and are amortized as interest expense over the term of the notes.

⁽²⁾


⁽³⁾	Upon the occurrence of a change in control (as defined in the indentures governing the Senior Notes), each holder of the notes will have the right to require L3 to repurchase all or any part of such holder’s notes at an offer price in cash equal to 101% of the aggregate principal amount plus accrued and unpaid interest, if any, to the date of purchase.

Repurchases, Redemptions and Maturities of Senior Notes

The repurchases, redemptions and maturities of Senior Notes are presented in the table below.



Note	Settlement Type	Date Settled	Aggregate Amount		Debt Retirement Charge		Cash Payments
			(in millions)
1.50% Senior Notes due 2017⁽¹⁾	Redemption	December 30, 2016	$	350	$	2	$	351
3.95% Senior Notes due 2016	Maturity	November 15, 2016	$	200	$	—	$	200
3.95% Senior Notes due 2016⁽²⁾	Redemption	May 20, 2016	$	300	$	5	$	305
3.95% Senior Notes due 2024	Tender Offer	December 22, 2015	$	300	$	1	$	297

__________________


⁽¹⁾	The 1.50% Senior Notes due 2017 were redeemed at a price equal to 100.323% of the principal amount thereof, plus accrued and unpaid interest to the redemption date. Interest ceased to accrue on and after the redemption date.


⁽²⁾	The 3.95% Senior Notes due 2016 were redeemed at a price equal to 101.475% of the principal amount thereof, plus accrued and unpaid interest. Interest ceased to accrue on and after May 20, 2016, and the only remaining right of holders of such Notes was to receive payment of the redemption price and accrued interest.

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Accumulated Other Comprehensive (Loss) Income (AOCI) (Tables)

12 Months Ended

Dec. 31, 2017

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Summary of AOCI Balances Including Amounts Reclassified from AOCI into Net Income

The changes in the AOCI balances, including amounts reclassified from AOCI into net income, are presented in the table below.



	Foreign currency translation			Unrealized (losses) gains on hedging instruments			Unrecognized (losses) gains and prior service cost, net			Total accumulated other comprehensive loss
	(in millions)
Balance at December 31, 2014	$	19		$	(5	)	$	(598	)	$	(584	)
Other comprehensive (loss) income before reclassifications, net of tax	(161		)	(15		)	81			(95		)
Amounts reclassified from AOCI, net of tax	41			12			52			105
Net current period other comprehensive (loss) income	(120		)	(3		)	133			10
Balance at December 31, 2015	$	(101	)	$	(8	)	$	(465	)	$	(574	)

Other comprehensive (loss) income before reclassifications, net of tax	(77		)	3			(119		)	(193		)
Amounts reclassified from AOCI, net of tax	—			11			30			41
Net current period other comprehensive (loss) income	(77		)	14			(89		)	(152		)
Balance at December 31, 2016	$	(178	)	$	6		$	(554	)	$	(726	)

Other comprehensive income (loss) before reclassifications, net of tax	124			7			(137		)	(6		)
Amounts reclassified from AOCI, net of tax	—			(4		)	45			41
Net current period other comprehensive income (loss)	124			3			(92		)	35
Balance at December 31, 2017	$	(54	)	$	9		$	(646	)	$	(691	)

Summary of Amounts Reclassified from AOCI into Net Income

Further details regarding the amounts reclassified from AOCI into net income are presented in the table below.



	Amount Reclassified from AOCI^(a)									Affected Line Item in the Audited Consolidated Statements of Operations
	Year Ended December 31,
Details About AOCI Components	2017			2016			2015
	(in millions)
Foreign currency translation adjustments:
MSI divestiture	$	—		$	—		$	(41	)	Loss related to business divestitures
	—			—			(41		)	Income from continuing operations before income taxes
	$	—		$	—		$	(41	)	Income from continuing operations

Gain (loss) on hedging instruments:
MSI divestiture	$	—		$	—		$	(2	)	Loss related to business divestitures
Other	5			(13		)	(16		)	Cost of sales-products
	5			(13		)	(18		)	Income from continuing operations before income taxes
	(1		)	2			6			Provision for income taxes
	$	4		$	(11	)	$	(12	)	Income from continuing operations

Amortization of defined benefit pension and postretirement items:
MSI divestiture	$	—		$	—		$	(14	)	Loss related to business divestitures
Net loss^(b)	(59		)	(48		)	(67		)
	(59		)	(48		)	(81		)	Income from continuing operations before income taxes
	14			18			29			Provision for income taxes
	$	(45	)	$	(30	)	$	(52	)	Income from continuing operations
Total reclassification for the period	$	(41	)	$	(41	)	$	(105	)	Income from continuing operations

__________________


^(a)	Amounts in parentheses indicate charges to the consolidated statements of operations.


^(b)	Amounts related to pension and postretirement benefit plans were reclassified from AOCI and recorded as a component of net periodic benefit cost (see Note 19 for additional information).

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Company's Assets and Liabilities at Fair Value on Recurring Basis

The following table presents the fair value hierarchy level for each of the Company’s assets and liabilities that are measured and recorded at fair value on a recurring basis.



	December 31, 2017						December 31, 2016
Description	Level 1⁽¹⁾		Level 2⁽²⁾		Level 3⁽³⁾		Level 1⁽¹⁾		Level 2⁽²⁾		Level 3⁽³⁾
	(in millions)
Assets
Cash equivalents	$	310	$	—	$	—	$	104	$	—	$	—
Derivatives (foreign currency forward contracts)	—		11		—		—		12		—
Total assets	$	310	$	11	$	—	$	104	$	12	$	—

Liabilities
Derivatives (foreign currency forward contracts)	$	—	$	1	$	—	$	—	$	6	$	—
Contingent consideration⁽⁴⁾	—		—		31		—		—		29
Total liabilities	$	—	$	1	$	31	$	—	$	6	$	29

__________________


⁽¹⁾	Level 1 is based on quoted market prices available in active markets for identical assets or liabilities as of the reporting date. Cash equivalents are primarily held in registered money market funds, which are valued using quoted market prices.


⁽²⁾	Level 2 is based on pricing inputs other than quoted prices in active markets, which are either directly or indirectly observable. The fair value is determined using a valuation model based on observable market inputs, including quoted foreign currency forward exchange rates and consideration of non-performance risk.


⁽³⁾	Level 3 is based on pricing inputs that are not observable and not corroborated by market data.

⁽⁴⁾

Changes to Contingent Consideration Obligations

The table below presents the changes to contingent consideration obligations during the year ended December 31, 2017.



	December 31, 2017
	(in millions)
Balance at beginning of period	$	29
Acquisitions	14
Changes in fair value of contingent consideration, net	(12		)
Balance at end of period	$	31

Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Investments, All Other Investments [Abstract]

Carrying Amounts and Estimated Fair Values of Company's Long-Term Debt and Foreign Currency Forward Contracts

The carrying amounts and estimated fair values of the Company’s other financial instruments are presented in the table below.



	December 31, 2017				December 31, 2016
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
	(in millions)
Senior Notes⁽¹⁾	$	3,330	$	3,502	$	3,325	$	3,526
Foreign currency forward contracts⁽²⁾	$	10	$	10	$	6	$	6

__________________


⁽¹⁾	The Company measures the fair value of its Senior Notes using Level 2 inputs based primarily on current market yields for its existing debt traded in the secondary market.


⁽²⁾	The Company measures the fair values of foreign currency forward contracts based on forward exchange rates. See Note 14 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts.

Derivative Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Notional Amounts of Company's Outstanding Foreign Currency Forward Contracts by Currency

The table below presents the notional amounts of the Company’s outstanding foreign currency forward contracts by currency at December 31, 2017.



Currency	Notional Amount
	(in millions)
U.S. dollar	$	108
Canadian dollar	100
Euro	84
British pound	15
Total	$	307

Location of Company's Derivative Instruments Recorded at Fair Value on the Consolidated Balance Sheets

The table below presents the location of the Company’s derivative instruments recorded at fair value on the consolidated balance sheets.



	December 31, 2017								December 31, 2016
	Other Current Assets		Other Assets		Other Current Liabilities		Other Liabilities		Other Current Assets		Other Assets		Other Current Liabilities		Other Liabilities
	(in millions)
Derivatives designated as hedging instruments:
Foreign currency forward contracts⁽¹⁾	$	11	$	—	$	1	$	—	$	10	$	2	$	6	$	—
Total derivative instruments	$	11	$	—	$	1	$	—	$	10	$	2	$	6	$	—

__________________


⁽¹⁾	See Note 12 for a description of the fair value hierarchy related to the Company's foreign currency forward contracts.

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=84234895&loc=d3e41641-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84234895&loc=d3e41678-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84234895&loc=d3e41638-113959

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579240-113959

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84234895&loc=d3e41620-113959

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(n)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

L3's Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Reconciliation of Basic and Diluted Earnings per Share (EPS)

A reconciliation of basic and diluted earnings per share (EPS) is presented in the table below.



	Year Ended December 31,
	2017			2016			2015
	(in millions, except per share data)
Reconciliation of net income (loss):
Net income (loss)	$	693		$	724		$	(225	)
Net income from continuing operations attributable to noncontrolling interests	(16		)	(14		)	(15		)
Net income (loss) attributable to L3’s common shareholders	$	677		$	710		$	(240	)
Earnings (loss) attributable to L3’s common shareholders:
Continuing operations	$	753		$	619		$	492
Discontinued operations, net of income tax	(76		)	91			(732		)
Net income (loss) attributable to L3’s common shareholders	$	677		$	710		$	(240	)
Earnings (loss) per share attributable to L3’s common shareholders:
Basic:
Weighted average common shares outstanding	78.0			77.4			80.7
Basic earnings (loss) per share:
Continuing operations	$	9.65		$	7.99		$	6.10
Discontinued operations, net of income tax	(0.97		)	1.18			(9.07		)
Net income (loss)	$	8.68		$	9.17		$	(2.97	)
Diluted:
Common and potential common shares:
Weighted average common shares outstanding	78.0			77.4			80.7
Effect of dilutive securities	1.6			1.4			1.2
Common and potential common shares	79.6			78.8			81.9
Diluted earnings (loss) per share:
Continuing operations	$	9.46		$	7.86		$	6.01
Discontinued operations, net of income tax	(0.95		)	1.15			(8.94		)
Net income (loss)	$	8.51		$	9.01		$	(2.93	)

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income from Continuing Operations Before Income Taxes

Income from continuing operations before income taxes is summarized in the table below.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Domestic	$	649	$	608	$	509
Foreign	222		196		130
Income from continuing operations before income taxes	$	871	$	804	$	639

Components of Current and Deferred Portions of Provision for Income Taxes on Continuing Operations

The components of the Company’s current and deferred portions of the provision for income taxes on continuing operations are presented in the table below.



	Year Ended December 31,
	2017			2016		2015
	(in millions)
Current income tax provision:
Federal	$	44		$	88	$	81
State and local	10			8		7
Foreign	56			48		26
Subtotal	110			144		114

Deferred income tax provision/(benefit):
Federal	(16		)	25		9
State and local	6			2		7
Foreign	2			—		2
Subtotal	(8		)	27		18
Total provision for income taxes	$	102		$	171	$	132

Reconciliation of Statutory Federal Income Tax Rate to Effective Income Tax Rate on Continuing Operations

A reconciliation of the statutory federal income tax rate to the effective income tax rate on continuing operations of the Company is presented in the table below.



	Year Ended December 31,
	2017		2016		2015
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%
State and local income taxes, net of federal income tax benefit	2.0		2.0		2.0
Foreign income taxes	(6.7	)	(3	)	(7.1	)
Manufacturing benefits	(1.4	)	(2.2	)	(2.2	)
Research and experimentation and other tax credits	(4.1	)	(4.6	)	(6.5	)
Resolution of tax contingencies	(0.4	)	(3.1	)	(1.4	)
Tax deductible dividends	(0.9	)	(1	)	(1.2	)
Equity compensation - excess income tax benefits	(2.3	)	(2.1	)	—
Goodwill impairment	—		—		1.9
Tax Reform	(9.1	)	—		—
Other, net	(0.4	)	0.3		0.2
Effective income tax rate on continuing operations	11.7	%	21.3	%	20.7	%

Components of Net Deferred Tax Assets and Liabilities

The significant components of the Company’s net deferred tax assets and liabilities are presented in the table below.



	December 31,
	2017			2016
	(in millions)
Deferred tax assets:
Inventoried costs	$	44		$	53
Compensation and benefits	94			139
Pension and postretirement benefits	281			413
Loss carryforwards	12			19
Tax credit carryforwards	5			6
Other	57			87
Deferred tax assets	493			717
Less: valuation allowance	(10		)	(12		)
Deferred tax assets, net of valuation allowance	483			705
Deferred tax liabilities:
Goodwill and other intangible assets	$	(514	)	$	(722	)
Income recognition on contracts in process	(24		)	(22		)
Property, plant and equipment	(59		)	(93		)
Other	(41		)	(55		)
Deferred tax liabilities	(638		)	(892		)
Total deferred tax liabilities, net of valuation allowance	$	(155	)	$	(187	)

Classification of Deferred Tax Assets and Liabilities

The classification of the Company’s deferred tax assets and liabilities are presented in the table below.



	December 31,
	2017			2016
	(in millions)
Non-current deferred tax assets	$	3		$	2
Non-current deferred tax liabilities	(158		)	(189		)
Total net deferred tax liabilities	$	(155	)	$	(187	)

Summary of Loss and Tax Credit Carryforwards



	Year Ended December 31, 2017
	Carryforwards				Valuation Allowances
	Gross		Tax Effected		Gross			Tax Effected			Expiration Periods
	(in millions)
Federal net operating loss carryforwards	$	29	$	6	$	(5	)	$	(1	)	2026-2036
Foreign net operating loss carryforwards	12		3		(6		)	(2		)	Indefinite
State net operating loss carryforwards	160		3		(135		)	(2		)	2018-2037
Total loss carryforwards			$	12				$	(5	)

State tax credit carryforwards	6		5		(5		)	(4		)	2018-2032
Total tax credit carryforwards			$	5				$	(4	)

Reconciliation of Change in Unrecognized Income Tax Benefits, Excluding Interest and Penalties



	2017			2016			2015
	(in millions)
Balance at January 1	$	110		$	124		$	150
Additions for tax positions related to the current year	14			16			14
Additions for tax positions related to prior years	66			2			2
Reductions for tax positions related to prior years	(4		)	(24		)	(34		)
Reductions for tax positions related to settlements with taxing authorities	—			(1		)	(1		)
Reduction for tax positions related to prior years as a result of a lapse of statute of limitations	(8		)	(7		)	(7		)
Balance at December 31	$	178		$	110		$	124

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Expense by Form of Award



	Year Ended December 31,
	2017			2016			2015
	(in millions)
Stock options	$	7		$	10		$	9
Restricted stock units	43			35			38
Performance units	7			4			2
Total before income taxes	57			49			49
Income taxes	(12		)	(18		)	(18		)
Total after income taxes	45			31			31
Less: Stock-based compensation recorded in discontinued operations, net of income taxes	1			1			1
Stock-based compensation recorded in continuing operations, net of income taxes	$	44		$	30		$	30

Company's Stock Option Activity and Changes

The table below presents a summary of the Company’s stock option activity at December 31, 2017 and changes during the year then ended.



	Number of Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
	(in thousands)				(in years)	(in millions)
Number of shares under option:
Outstanding at January 1, 2017	2,847.5		$	99.54	6.1	$150
Options granted	470.5		174.53
Options exercised	(521.3	)	90.13
Options forfeited	(97.8	)	120.59
Outstanding at December 31, 2017	2,698.9		$	113.67	5.7	$227
Vested and expected to vest at December 31, 2017⁽¹⁾	2,582.5		$	110.21	5.5	$226
Exercisable at December 31, 2017	1,762.4		$	95.80	4.5	$180

__________________


⁽¹⁾	Represents outstanding options reduced by expected forfeitures for options not fully vested.

Weighted Average Assumptions in Valuation Model

The weighted average assumptions used in the valuation model are presented in the table below.



	2017 Grants		2016 Grants		2015 Grants
Expected holding period (in years)	5.2		5.0		5.0
Expected volatility	19.9	%	21.3	%	21.4	%
Expected dividend yield	2.0	%	2.8	%	2.4	%
Risk-free interest rate	2.0	%	1.1	%	1.5	%

Company's Nonvested Restricted Stock Unit Awards and Changes

The table below presents a summary of the Company’s nonvested restricted stock unit awards at December 31, 2017 and changes during the year then ended.



	Number of Shares		Weighted Average Grant Date Fair Value
	(in thousands)
Nonvested balance at January 1, 2017	977.9		$	119.55
Granted	305.6		169.23
Vested	(318.4	)	114.46
Forfeited	(62.4	)	134.56
Nonvested balance at December 31, 2017	902.7		$	137.12

Company's Performance Unit Awards Based on Expected Performance

The table below presents a summary of the Company’s performance unit awards based on expected performance at December 31, 2017 and changes during the year then ended.



	Payable in Shares (EPS)
	Number of Units		Weighted Average Grant Date Fair Value
	(in thousands)
Outstanding at January 1, 2017	124.7		$	120.83
Granted	33.9		168.80
Increase due to expected performance	29.7		146.89
Vested	(48.4	)	129.03
Forfeited	(7.8	)	121.06
Outstanding at December 31, 2017	132.1		$	135.99

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Future Minimum Payments under Non-Cancelable Operating Leases

The following table presents future minimum payments under non-cancelable operating leases with initial or remaining terms in excess of one year at December 31, 2017.



	Real Estate			Equipment		Total
	(in millions)
2018	$	101		$	5	$	106
2019	81			3		84
2020	106			2		108
2021	60			—		60
2022	57			—		57
Thereafter	236			—		236
Total minimum payments required	641			10		651
Sublease rentals under non-cancelable leases	(9		)	—		(9		)
Net minimum payments required	$	632		$	10	$	642

Pension and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2017

Retirement Benefits [Abstract]

Changes in Benefit Obligations, Plan Assets and Funded Status and Aggregate Balance Sheet Impact



	Pension Plans						Postretirement Benefit Plans
	2017			2016			2017			2016
	(in millions)
Change in benefit obligation:
Benefit obligation at the beginning of the year	$	3,758		$	3,448		$	177		$	184
Service cost	97			94			2			2
Interest cost	142			135			5			6
Plan participants’ contributions	2			2			5			4
Amendments	—			15			—			(3		)
Actuarial loss (gain)	391			181			(13		)	(3		)
Foreign currency exchange rate changes	22			9			2			—
Curtailments and special termination benefits	2			2			—			—
Benefits paid	(186		)	(128		)	(13		)	(13		)
Benefit obligation at the end of the year	$	4,228		$	3,758		$	165		$	177
Change in plan assets:
Fair value of plan assets at the beginning of the year	$	2,721		$	2,552		$	60		$	57
Actual return on plan assets	391			189			8			5
Employer contributions	97			97			7			7
Plan participants’ contributions	2			2			5			4
Foreign currency exchange rate changes	22			9			—			—
Benefits paid	(186		)	(128		)	(13		)	(13		)
Fair value of plan assets at the end of the year	$	3,047		$	2,721		$	67		$	60
Unfunded status at the end of the year	$	(1,181	)	$	(1,037	)	$	(98	)	$	(117	)

Assets and (liabilities) recognized on the consolidated balance sheets consist of:
Non-current assets	$	48		$	37		$	—		$	—
Current liabilities	(6		)	(6		)	(8		)	(8		)
Non-current liabilities	(1,223		)	(1,068		)	(90		)	(109		)
	$	(1,181	)	$	(1,037	)	$	(98	)	$	(117	)

Net Loss and Prior Service Cost Balances in Accumulated Other Comprehensive Loss Account



	Pension Plans				Postretirement Benefit Plans
	2017		2016		2017			2016
	(in millions)
Net loss (gain)	$	1,035	$	896	$	(3	)	$	(12	)
Prior service cost (credit)	10		14		(27		)	(4		)
Total amount recognized	$	1,045	$	910	$	(30	)	$	(16	)

Pension Plans with an Accumulated Benefit Obligation in Excess of Fair Value of Plan Assets

The table below presents information for the pension plans with an ABO in excess of the fair value of plan assets at December 31, 2017 and 2016.



	Pension Plans
	2017		2016
	(in millions)
Projected benefit obligation	$	3,875	$	3,528
Accumulated benefit obligation	$	3,490	$	3,192
Fair value of plan assets	$	2,651	$	2,456

Weighted Average Assumptions Used to Determine Benefit Obligations

The table below summarizes the weighted average assumptions used to determine the benefit obligations for the Company’s pension and postretirement plans disclosed at December 31, 2017 and 2016.



	Pension Plans						Postretirement Benefit Plans
	2017			2016			2017			2016
Benefit obligations:
Discount rate	3.78	%	⁽¹⁾	4.40	%	⁽¹⁾	3.59	%	⁽²⁾	4.05	%	⁽²⁾
Rate of compensation increase	3.50	%	⁽³⁾	3.50	%	⁽³⁾

__________________


⁽¹⁾	The weighted average discount rate assumptions used at December 31, 2017 and 2016 were comprised of separate assumptions determined by country of 3.81% and 4.45% for the U.S. based plans, respectively, and 3.39% and 3.79% for the Canadian based plans, respectively.


⁽²⁾	The weighted average discount rate assumptions used at December 31, 2017 and 2016 were comprised of separate assumptions determined by country of 3.63% and 4.11% for the U.S. based plans, respectively, and 3.33% and 3.64% for the Canadian based plans, respectively.


⁽³⁾	The weighted average rate of compensation increase assumptions were comprised of separate assumptions determined by country of 3.5% for both the U.S. based plans and Canadian based plans at December 31, 2017 and 2016.

Components of Net Periodic Benefit Cost

The following table summarizes the components of net periodic benefit cost for the Company’s pension and postretirement benefit plans for the years ended December 31, 2017, 2016 and 2015.



	Pension Plans									Postretirement Benefit Plans
	2017			2016			2015			2017			2016			2015
	(in millions)
Components of net periodic benefit cost:
Service cost ⁽¹⁾	$	97		$	94		$	112		$	2		$	2		$	3
Interest cost	142			135			149			5			6			7
Expected return on plan assets ⁽¹⁾	(197		)	(186		)	(194		)	(4		)	(4		)	(5		)
Amortization of prior service cost (credits)	1			—			1			(1		)	(2		)	(2		)
Amortization of net loss (gains)	61			52			68			(2		)	(2		)	—
Curtailment loss and special termination benefits ⁽²⁾	6			2			3			—			—			—
Net periodic benefit cost	$	110		$	97		$	139		$	—		$	—		$	3

__________________

⁽¹⁾


⁽²⁾	During the year ended December 31, 2017, the curtailment loss and special termination benefits charge is primarily due to a pension curtailment charge in connection with the decision to discontinue future service accruals for substantially all salaried employee defined benefit plans effective January 1, 2019.

Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss)



	Pension Plans									Postretirement Benefit Plans
	2017			2016			2015			2017			2016			2015
	(in millions)
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss):
Net loss (gain)	$	200		$	179		$	(132	)	$	(17	)	$	(4	)	$	(7	)
Prior service (cost) credit	(4		)	15			—			—			(2		)	—
Amortization of net (loss) gain	(61		)	(52		)	(68		)	2			2			—
Amortization of prior service (cost) credit	(1		)	—			(1		)	1			2			2
Total recognized in other comprehensive income (loss)	134			142			(201		)	(14		)	(2		)	(5		)
Total recognized in net periodic benefit cost and other comprehensive income (loss)	$	244		$	239		$	(62	)	$	(14	)	$	(2	)	$	(2	)

Amounts Expected to be Amortized from Accumulated OCI and Recognized as Components of Net Periodic Benefit Costs

The following table summarizes the amounts expected to be amortized from accumulated OCI and recognized as components of net periodic benefit costs during 2018.



	Pension Plans		Postretirement Benefit Plans			Total
	(in millions)
Net loss (gain)	$	74	$	(3	)	$	71
Prior service credit	—		(1		)	(1		)
	$	74	$	(4	)	$	70

Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost

The table below summarizes the weighted average assumptions used to determine the net periodic benefit cost for the years ended December 31, 2017, 2016 and 2015.



	Pension Plans									Postretirement Benefit Plans
	2017			2016			2015			2017			2016			2015
Discount rates:
Benefit obligation	4.40	%	⁽¹⁾	4.67	%	⁽¹⁾	4.14	%	⁽¹⁾	4.05	%	⁽⁴⁾	4.22	%	⁽⁴⁾	3.70	%	⁽⁴⁾
Service cost	4.55	%		4.83	%		—	%	⁽⁵⁾	4.21	%		4.37	%		—	%	⁽⁵⁾
Interest cost	3.84	%		3.95	%		—	%	⁽⁵⁾	3.26	%		3.26	%		—	%	⁽⁵⁾
Expected long-term return on plan assets	7.92	%	⁽²⁾	7.92	%	⁽²⁾	8.14	%	⁽²⁾	7.43	%		7.42	%		7.65	%
Rate of compensation increase	3.50	%	⁽³⁾	3.50	%	⁽³⁾	3.50	%	⁽³⁾

__________________


⁽¹⁾	The weighted average discount rate assumptions used for the years ended December 31, 2017, 2016, and 2015 were comprised of separate assumptions determined by country of 4.45%, 4.73% and 4.20% for the U.S. based plans and 3.79%, 3.93% and 3.90% for the Canadian based plans, respectively.


⁽²⁾	The weighted average expected long-term return on plan assets assumptions used were comprised of separate assumptions determined by country of 8.00% for each of the years ended December 31, 2017 and 2016 and 8.25% for the year ended December 31, 2015 for the U.S. based plans and 7.25% for the Canadian based plans for the years ended December 31, 2017, 2016 and 2015.


⁽³⁾	The weighted average rate of compensation increase assumptions used for the years ended December 31, 2017, 2016 and 2015 were comprised of separate assumptions determined by country of 3.50% for both the U.S and Canadian based plans.


⁽⁴⁾	The weighted average discount rate assumptions used for the years ended December 31, 2017, 2016 and 2015 were comprised of separate assumptions determined by country of 4.11%, 4.28% and 3.70% for the U.S. based plans and 3.64%, 3.74% and 3.70% for the Canadian based plans, respectively.


⁽⁵⁾	Not applicable as the Company changed to the spot rate approach beginning in 2016 as described above.

Effect of One Percentage Point Change in Assumed Health Care Cost Trend Rates

A one percentage point change in the assumed health care cost trend rates would have the following effects:



	1 percentage point
	Increase		Decrease
	(in millions)
Effect on total service and interest cost	$	—	$	—
Effect on postretirement benefit obligations	$	5	$	(4	)

Allowable Range for Each Major Category of the Plans' Assets and Weighted-Average Asset Allocations by Asset Category



	U.S.					Canada
Asset Category	Range	2017		2016		Range	2017		2016
Domestic equity⁽¹⁾	30%-60%	47	%	55	%	—	15	%	15	%
International equity⁽²⁾	10%-20%	11		10		—	47		62
Total equities	45%-75%	58		65		40%-80%	62		77
Fixed income securities	20%-40%	28		22		—	25		13
Other, primarily cash and cash equivalents	0%-15%	7		5		—	13		10
Total fixed income securities and cash and cash equivalents	NA	NA		NA		20%-60%	38		23
Real estate securities	0%-15%	7		8		—	—		—
Total		100	%	100	%		100	%	100	%

__________________


⁽¹⁾	Domestic equities for Canadian plans refers to equities of Canadian companies.


⁽²⁾	International equities for Canadian plans includes equities of U.S. companies.

NA - Not applicable. The Company’s Master Pension Trust Investment Policy does not provide an allocation percentage range to fixed income securities and cash and cash equivalents.

Fair Value of the Company's Pension Plans' and Postretirement Benefit Plans' Assets

The table below presents the fair value of the Company’s postretirement benefit plans’ assets by asset category segregated by level within the fair value hierarchy, as described below.



	Postretirement Benefit Plans’ Assets
	Fair Value Measured At December 31, 2017								Fair Value Measured At December 31, 2016
Asset Category	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
	(in millions)
Equity securities⁽¹⁾:
U.S. Equity	$	38	$	—	$	—	$	38	$	37	$	—	$	—	$	37
International Equity	2		—		—		2		1		—		—		1
Fixed Income — Investment Grade⁽²⁾	10		3		—		13		8		3		—		11
Fixed Income — High Yield⁽³⁾	—		3		—		3		—		2		—		2
Real Estate Investment Trusts⁽⁴⁾	3		—		—		3		3		—		—		3
Other⁽⁵⁾	—		5		—		5		—		3		—		3
Total assets at fair value	$	53	$	11	$	—	$	64	$	49	$	8	$	—	$	57
Other investments measured at net asset value⁽⁶⁾⁽⁷⁾							3								3
Total							$	67							$	60

__________________


⁽¹⁾	Equity securities consist of investments in common stock of U.S. and international companies. The fair value of equity securities is based on quoted market prices available in active markets at the close of a trading day, primarily the NYSE, NASDAQ, and various international exchanges.

⁽²⁾


⁽³⁾	Fixed Income — High Yield consists of investments in corporate high-yield bonds from various industries. The fair values of these investments are based on yields currently available on comparable bonds of issuers with similar credit ratings, quoted prices of similar bonds in an active market, or cash flows based on observable inputs.


⁽⁴⁾	REITs consist of securities that trade on the major exchanges and invest directly, either through properties or mortgages.


⁽⁵⁾	Other consists primarily of money market accounts, which invest primarily in short-term, high quality money market securities such as government obligations, commercial paper, time deposits and certificates of deposit.


⁽⁶⁾	In accordance with ASU 2015-07, certain investments that are measured at fair value using the NAV per share (or its equivalent)practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position.

⁽⁷⁾

The table below presents the fair value of the Company’s pension plans’ assets by asset category segregated by level within the fair value hierarchy, as described below.



	U.S. Pension Plans’ Assets									Canadian Pension Plans’ Assets
	Fair Value Measured At December 31, 2017									Fair Value Measured At December 31, 2017
Asset Category	Level 1		Level 2		Level 3		Total			Level 1		Level 2		Level 3		Total
	(in millions)
Equity securities⁽¹⁾:
U.S. Equity	$	1,297	$	—	$	—	$	1,297		$	71	$	—	$	—	$	71
International Equity	87		—		—		87			105		—		—		105
Fixed Income — Investment Grade⁽²⁾	329		205		—		534			—		—		—		—
Fixed Income — High Yield⁽³⁾	—		219		—		219			—		—		—		—
Real Estate Investment Trusts⁽⁴⁾	196		—		—		196			—		—		—		—
Other⁽⁵⁾	—		198		—		198			8		37		—		45
Total assets at fair value	$	1,909	$	622	$	—	$	2,531		$	184	$	37	$	—	$	221
Liabilities for unsettled trades, net							(30		)							—
Other investments measured at net asset value⁽⁶⁾⁽⁷⁾							203									122
Total							$	2,704								$	343



	U.S. Pension Plans’ Assets									Canadian Pension Plans’ Assets
	Fair Value Measured At December 31, 2016									Fair Value Measured At December 31, 2016
Asset Category	Level 1		Level 2		Level 3		Total			Level 1		Level 2		Level 3		Total
	(in millions)
Equity securities⁽¹⁾:
U.S. Equity	$	1,331	$	—	$	—	$	1,331		$	79	$	—	$	—	$	79
International Equity	85		—		—		85			104		—		—		104
Fixed Income — Investment Grade⁽²⁾	255		159		—		414			—		—		—		—
Fixed Income — High Yield⁽³⁾	—		136		—		136			—		—		—		—
Real Estate Investment Trusts⁽⁴⁾	193		—		—		193			—		—		—		—
Other⁽⁵⁾	—		114		—		114			5		27		—		32
Total assets at fair value	$	1,864	$	409	$	—	$	2,273		$	188	$	27	$	—	$	215
Liabilities for unsettled trades, net							(23		)							—
Other investments measured at net asset value⁽⁶⁾⁽⁷⁾							171									85
Total							$	2,421								$	300

__________________


⁽¹⁾	Equity securities consist of investments in common stock of U.S. and international companies. The fair value of equity securities is based on quoted market prices available in active markets at the close of a trading day, primarily the New York Stock Exchange (NYSE), National Association of Securities Dealers Automated Quotations (NASDAQ), and various international exchanges.

⁽²⁾


⁽³⁾	Fixed Income — High Yield consists of investments in corporate high-yield bonds from various industries. The fair values of these investments are based on yields currently available on comparable bonds of issuers with similar credit ratings, quoted prices of similar bonds in an active market, or cash flows based on observable inputs.


⁽⁴⁾	Real Estate Investment Trusts (REITs) consist of securities that trade on the major exchanges and invest directly in real estate, either through properties or mortgages.


⁽⁵⁾	Other consists primarily of: (1) money market accounts, which invest primarily in short-term, high quality money market securities such as government obligations, commercial paper, time deposits and certificates of deposit, and are classified as Level 2, and (2) cash, which is classified as Level 1.


⁽⁶⁾	In accordance with ASU 2015-07, certain investments that are measured at fair value using the net asset value (NAV) per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position.

⁽⁷⁾

Estimated Future Benefit Payments

The following table presents expected pension and postretirement benefit payments and expected postretirement subsidies due to the Medicare Prescription Drug Improvement and Modernization Act of 2003, which reflect expected future service, as appropriate.



			Postretirement Benefits
	Pension Benefits		Benefit Payments		Subsidy Receipts
	(in millions)
2018	$	158	$	12	$	—
2019	165		12		—
2020	175		13		—
2021	185		13		—
2022	194		12		—
Years 2023 - 2027	1,128		55		1

Cash Contributions and Expenses under Multi-Employer Benefit Plans

Under these plans, the Company contributed cash and recorded expenses for each of its individually significant plans and all of its other plans in aggregate as noted in the table below.



	EIN/Pension Plan Number	Pension Protection Act Zone Status⁽¹⁾		FIP/RP⁽²⁾ Status Pending/ Implemented	Contributions by L3⁽⁷⁾									Surcharge Imposed	Expiration Date of Collective- Bargaining Agreement
Pension Fund	EIN/Pension Plan Number	2017	2016	FIP/RP⁽²⁾ Status Pending/ Implemented	2017			2016			2015			Surcharge Imposed	Expiration Date of Collective- Bargaining Agreement
IAM National Pension Fund	51-6031295/002	Green	Green	No	$	27	⁽³⁾	$	26	⁽⁴⁾	$	23	⁽⁴⁾	No	4/29/2018 to 9/30/2020⁽⁵⁾
Other Pension Funds⁽⁶⁾					—			—			—
Total contributions					$	27		$	26		$	23

__________________


⁽¹⁾	A zone status rating of green indicates the plan is at least 80% funded.


⁽²⁾	Funding improvement plan or rehabilitation plan.


⁽³⁾	At the date the audited financial statements for the Company were issued, the Form 5500 for the plan year ended December 31, 2017 was not available.


⁽⁴⁾	Represents 5% of total plan contributions for the years ended December 31, 2016 and 2015 based on Form 5500.


⁽⁵⁾	The Company is a party to multiple bargaining agreements for multiple projects that require contributions into the IAM National Pension Fund. The most significant of these agreements, expiring April 28, 2019, covers multiple programs in the Company’s ISRS reportable segment and represents 61% of 2017 contributions.


⁽⁶⁾	Consists of three pension funds in which the Company’s contributions are individually, and in the aggregate, insignificant.


⁽⁷⁾	These contributions include amounts attributable to discontinued operations of approximately $26 million for the years ended December 31, 2017 and 2016 and $22 million for the year ended December 31, 2015.

Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2017

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information



	Year Ended December 31,
	2017		2016		2015
	(in millions)
Interest paid	$	165	$	162	$	182
Income tax payments	$	163	$	120	$	130
Income tax refunds	$	16	$	8	$	8

Segment Information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Summary of Segment Information

The tables below present net sales, operating income, depreciation and amortization, capital expenditures and total assets by reportable segment.



	Year Ended December 31,
	2017			2016			2015
	(in millions)
Net Sales
Products
ISRS	$	2,540		$	2,662		$	2,696
C&NS	2,424			2,238			2,244
Electronic Systems	1,814			1,617			1,716
Elimination of intercompany sales	(45		)	(64		)	(56		)
Total products sales	6,733			6,453			6,600

Services
ISRS	$	1,463		$	1,450		$	1,403
C&NS	717			678			637
Electronic Systems	695			653			612
Elimination of intercompany sales	(35		)	(24		)	(21		)
Total services sales	2,840			2,757			2,631
Consolidated total	$	9,573		$	9,210		$	9,231



	Year Ended December 31,
	2017		2016		2015
	(in millions)

Operating income
ISRS	$	348	$	362	$	312
C&NS	362		298		288
Electronic Systems	321		298		289
Segment total	1,031		958		889
Goodwill impairment charges⁽¹⁾	—		—		(46		)
Loss related to business divestitures⁽²⁾	—		—		(31		)
Consolidated total	$	1,031	$	958	$	812

Depreciation and amortization
ISRS	$	87	$	80	$	83
C&NS	66		63		68
Electronic Systems	72		55		52
Consolidated total	$	225	$	198	$	203

Capital Expenditures
ISRS	$	74	$	83	$	77
C&NS	76		51		48
Electronic Systems	52		66		64
Corporate	22		10		6
Consolidated total	$	224	$	210	$	195

Total Assets
ISRS	$	4,135	$	4,117	$	4,219
C&NS	3,505		3,258		3,222
Electronic Systems	3,939		3,542		3,159
Corporate	709		467		345
Assets held for sale	135		—		—
Assets of discontinued operations	306		481		1,124
Consolidated total	$	12,729	$	11,865	$	12,069

__________________


⁽¹⁾	Represents non-cash goodwill impairment charges recorded during 2015 of $46 million related to a business retained by L3 in connection with the sale of the NSS segment.


⁽²⁾	See Note 3 for information regarding the Company’s business divestitures.

Property, Plant and Equipment by Geographic Area

The table below presents property, plant and equipment, net by geographic area.



	Year Ended December 31,
	2017		2016
	(in millions)
United States	$	936	$	960
All Other	174		147
Total	$	1,110	$	1,107

Company's Sales Attributable to U.S. Customers and International Customers

The Company’s sales attributable to U.S. and international customers, based on location of the customer, are summarized in the table below.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
U.S.	$	7,344	$	6,947	$	6,734
International:
United Kingdom	335		331		336
Canada	280		297		281
Australia	268		254		321
China	167		67		83
South Korea	134		127		207
Japan	125		81		95
France	84		75		62
Other	836		1,031		1,112
Total international	2,229		2,263		2,497
Consolidated	$	9,573	$	9,210	$	9,231

Net Sales to Principal Customers

Net sales to principal customers are summarized in the table below.



	Year Ended December 31,
	2017		2016	2015
	(in millions)
U.S. Government agencies⁽¹⁾	$	6,697	6,399	$	6,120
Commercial	1,456		1,280	1,373
Foreign governments⁽¹⁾	1,420		1,531	1,738
Consolidated	$	9,573	9,210	$	9,231

__________________


⁽¹⁾	Includes sales for which the Company is the prime contractor as well as sales based on the ultimate end customer for which the Company is a subcontractor.

Severance and Restructuring Related Costs (Tables)

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Severance and Restructuring Costs Incurred by Reportable Segment

Severance and restructuring related costs are reported within cost of sales on the consolidated statements of operations. Severance and restructuring related costs incurred by reportable segment are presented in the table below.



	Year Ended December 31,
	2017		2016		2015
	(in millions)
ISRS⁽¹⁾⁽²⁾	$	38	$	5	$	8
C&NS⁽³⁾	52		8		7
Electronic Systems⁽²⁾	11		4		3
Consolidated	$	101	$	17	$	18

__________________


⁽¹⁾	The severance and restructuring related costs incurred during the year ended December 31, 2017 include a $12 million loss on the sale of a building in Garland, Texas in the fourth quarter of 2017.


⁽²⁾	The severance and restructuring related costs incurred during the year ended December 31, 2017 include $1 million and $5 million of salaried employee pension plan curtailment losses for Electronic Systems and ISRS segments, respectively. See Note 19 for additional information.


⁽³⁾	The severance and restructuring related costs incurred during the year ended December 31, 2017 exclude a pre-tax gain of $42 million on the sale of the Company's property in San Carlos, California in the second quarter of 2017.



	December 31, 2017
	(in millions)
Balance at beginning of period	$	9
Additional provisions	101
Cash payments	(87		)
Balance at end of period	$	23

Unaudited Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Unaudited Quarterly Financial Data



	First Quarter		Second Quarter		Third Quarter⁽¹⁾		Fourth Quarter⁽²⁾
	(in millions, except per share data)
2017
Sales	$	2,321	$	2,385	$	2,293	$	2,574
Operating income	237		294		232		268
Income from continuing operations	157		195		146		271
Net income	168		207		25		293
Net income attributable to L3	164		202		22		289
Basic EPS from continuing operations⁽³⁾	1.97		2.44		1.83		3.42
Basic EPS⁽³⁾	2.11		2.59		0.28		3.70
Diluted EPS from continuing operations⁽³⁾	1.93		2.39		1.79		3.34
Diluted EPS⁽³⁾	2.07		2.54		0.28		3.62

2016
Sales	$	2,065	$	2,318	$	2,184	$	2,643
Operating income	244		220		211		283
Income from continuing operations	163		134		149		187
Net income	230		151		151		192
Net income attributable to L3	227		147		148		188
Basic EPS from continuing operations⁽³⁾	2.06		1.68		1.89		2.37
Basic EPS⁽³⁾	2.92		1.90		1.91		2.43
Diluted EPS from continuing operations⁽³⁾	2.02		1.66		1.85		2.32
Diluted EPS⁽³⁾	2.87		1.88		1.88		2.38

__________________


⁽¹⁾	The Company recorded a goodwill impairment charge of $187 million or $1.67 per diluted share for the Vertex Aerospace reporting unit in 2017, which is reported in discontinued operations.


⁽²⁾	Provision for income taxes for the fourth quarter of 2017, includes estimated tax benefits of $79 million or $0.99 per diluted share, related to the enactment of U.S. Tax Reform in December 2017.


⁽³⁾	EPS in each quarter is computed using the weighted-average number of shares outstanding during that quarter, while EPS for the full year is computed using the weighted-average number of shares outstanding during the year. Therefore, the sum of the four quarters’ EPS may not equal the full year computed EPS.

Financial Information of L3 and Its Subsidiaries (Tables)

12 Months Ended

Dec. 31, 2017

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Condensed Combining Balance Sheets



	L3		Guarantor Subsidiaries		Non- Guarantor Subsidiaries		Eliminations			Consolidated L3
	(in millions)
Condensed Combining Balance Sheets:
At December 31, 2017:
Current assets:
Cash and cash equivalents	$	432	$	16	$	285	$	(71	)	$	662
Billed receivables, net	266		244		213		—			723
Contracts in process	706		912		315		—			1,933
Prepaid expenses and other current assets	330		235		124		—			689
Assets held for sale	—		135		—		—			135
Assets of discontinued operations	306		—		—		—			306
Total current assets	2,040		1,542		937		(71		)	4,448
Goodwill	2,099		2,932		1,584		—			6,615
Other assets	658		687		321		—			1,666
Investment in and amounts due from consolidated subsidiaries	5,662		6,310		—		(11,972		)	—
Total assets	$	10,459	$	11,471	$	2,842	$	(12,043	)	$	12,729
Current liabilities	$	811	$	832	$	564	$	(71	)	$	2,136
Liabilities held for sale	—		17		—		—			17
Liabilities of discontinued operations	226		—		—		—			226
Amounts due to consolidated subsidiaries	—		—		391		(391		)	—
Other long-term liabilities	1,009		729		131		—			1,869
Long-term debt	3,330		—		—		—			3,330
Total liabilities	5,376		1,578		1,086		(462		)	7,578
L3 shareholders’ equity	5,083		9,893		1,756		(11,649		)	5,083
Noncontrolling interests	—		—		—		68			68
Total equity	5,083		9,893		1,756		(11,581		)	5,151
Total liabilities and equity	$	10,459	$	11,471	$	2,842	$	(12,043	)	$	12,729



	L3		Guarantor Subsidiaries		Non- Guarantor Subsidiaries		Eliminations			Consolidated L3
	(in millions)
At December 31, 2016:
Current assets:
Cash and cash equivalents	$	262	$	5	$	203	$	(107	)	$	363
Billed receivables, net	261		261		178		—			700
Contracts in process	694		936		228		—			1,858
Prepaid expenses and other current assets	236		145		124		—			505
Assets of discontinued operations	481		—		—		—			481
Total current assets	1,934		1,347		733		(107		)	3,907
Goodwill	2,110		2,785		1,479		—			6,374
Other assets	705		592		287		—			1,584
Investment in and amounts due from consolidated subsidiaries	5,653		5,563		—		(11,216		)	—
Total assets	$	10,402	$	10,287	$	2,499	$	(11,323	)	$	11,865
Current liabilities	$	789	$	833	$	444	$	(107	)	$	1,959
Liabilities of discontinued operations	235		—		—		—			235
Amounts due to consolidated subsidiaries	—		—		832		(832		)	—
Other long-term liabilities	1,500		192		30		—			1,722
Long-term debt	3,325		—		—		—			3,325
Total liabilities	5,849		1,025		1,306		(939		)	7,241
L3 shareholders’ equity	4,553		9,262		1,193		(10,455		)	4,553
Noncontrolling interests	—		—		—		71			71
Total equity	4,553		9,262		1,193		(10,384		)	4,624
Total liabilities and equity	$	10,402	$	10,287	$	2,499	$	(11,323	)	$	11,865

Condensed Combining Statements of Operations



	L3			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated L3
	(in millions)
Condensed Combining Statements of Operations:
For the year ended December 31, 2017:
Total net sales	$	3,520		$	4,852		$	1,581		$	(380	)	$	9,573
Total cost of sales	(3,169		)	(4,446		)	(1,307		)	380			(8,542		)
Operating income	351			406			274			—			1,031
Interest expense	(168		)	—			(1		)	—			(169		)
Interest and other income (loss), net	6			(8		)	11			—			9
Income from continuing operations before income taxes	189			398			284			—			871
Provision for income taxes	(22		)	(47		)	(33		)	—			(102		)
Equity in net income of consolidated subsidiaries	586			144			—			(730		)	—
Income from continuing operations	753			495			251			(730		)	769
Loss from discontinued operations, net of income tax	(76		)	—			—			—			(76		)
Net income	677			495			251			(730		)	693
Net income attributable to noncontrolling interests	—			—			—			(16		)	(16		)
Net income attributable to L3	$	677		$	495		$	251		$	(746	)	$	677
Comprehensive income attributable to L3	$	712		$	604		$	378		$	(982	)	$	712

For the year ended December 31, 2016:
Total net sales	$	3,351		$	4,842		$	1,348		$	(331	)	$	9,210
Total cost of sales	(3,064		)	(4,406		)	(1,113		)	331			(8,252		)
Operating income	287			436			235			—			958
Interest expense	(164		)	—			—			—			(164		)
Interest and other income (loss), net	9			(3		)	11			—			17
Debt retirement charges	(7		)	—			—			—			(7		)
Income from continuing operations before income taxes	125			433			246			—			804
Provision for income taxes	(26		)	(92		)	(53		)	—			(171		)
Equity in net income of consolidated subsidiaries	520			130			—			(650		)	—
Income from continuing operations	619			471			193			(650		)	633
Income from discontinued operations, net of income tax	91			—			—			—			91
Net income	710			471			193			(650		)	724
Net income attributable to noncontrolling interests	—			—			—			(14		)	(14		)
Net income attributable to L3	$	710		$	471		$	193		$	(664	)	$	710
Comprehensive income attributable to L3	$	558		$	409		$	116		$	(525	)	$	558

For the year ended December 31, 2015:
Total net sales	$	3,268		$	4,870		$	1,444		$	(351	)	$	9,231
Total cost of sales	(3,017		)	(4,429		)	(1,247		)	351			(8,342		)
Goodwill impairment charges	—			(26		)	(20		)	—			(46		)
(Loss) gain related to business divestitures	(13		)	(31		)	13			—			(31		)
Operating income	238			384			190			—			812
Interest expense	(161		)	(1		)	—			—			(162		)
Interest and other income (loss), net	3			(15		)	2			—			(10		)
Debt retirement charge	(1		)	—			—			—			(1		)
Income from continuing operations before income taxes	79			368			192			—			639
Provision for income taxes	(16		)	(76		)	(40		)	—			(132		)
Equity in net income of consolidated subsidiaries	429			73			—			(502		)	—
Income from continuing operations	492			365			152			(502		)	507
Loss from discontinued operations, net of income tax	(732		)	—			—			—			(732		)
Net (loss) income	(240		)	365			152			(502		)	(225		)
Net income attributable to noncontrolling interests	—			—			—			(15		)	(15		)
Net (loss) income attributable to L3	$	(240	)	$	365		$	152		$	(517	)	$	(240	)
Comprehensive (loss) income attributable to L3	$	(230	)	$	255		$	41		$	(296	)	$	(230	)

Condensed Combining Statements of Cash Flows



	L3			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated L3
	(in millions)
Condensed Combining Statements of Cash Flows:
For the year ended December 31, 2017:
Operating activities:
Net cash from operating activities from continuing operations	$	374		$	426		$	263		$	(78	)	$	985
Investing activities:
Business acquisitions, net of cash acquired	(316		)	—			—			—			(316		)
Proceeds from sale of businesses, net of closing date cash balances	17			—			1			—			18
Other investing activities	(92		)	(38		)	(25		)	—			(155		)
Net cash used in investing activities from continuing operations	(391		)	(38		)	(24		)	—			(453		)
Financing activities:
Common stock repurchased	(180		)	—			—			—			(180		)
Dividends paid on L3’s common stock	(236		)	—			—			—			(236		)
Other financing activities	490			(377		)	(177		)	114			50
Net cash from (used in) financing activities from continuing operations	74			(377		)	(177		)	114			(366		)
Effect of foreign currency exchange rate changes on cash	—			—			20			—			20
Net increase in cash and cash equivalents of discontinued operations	113			—			—			—			113
Net increase in cash	170			11			82			36			299
Cash and cash equivalents, beginning of the year	262			5			203			(107		)	363
Cash and cash equivalents, end of the year	$	432		$	16		$	285		$	(71	)	$	662



	L3			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated L3
	(in millions)
For the year ended December 31, 2016:
Operating activities:
Net cash from operating activities from continuing operations	$	440		$	509		$	259		$	(186	)	$	1,022
Investing activities:
Business acquisitions, net of cash acquired	(388		)	—			—			—			(388		)
Proceeds from sale of businesses, net of closing date cash cash balances	563			—			(2		)	—			561
Other investing activities	(63		)	(77		)	(43		)	—			(183		)
Net cash from (used in) investing activities from continuing operations	112			(77		)	(45		)	—			(10		)
Financing activities:
Proceeds from sale of senior notes	547			—			—			—			547
Redemption of senior notes	(856		)	—			—			—			(856		)
Common stock repurchased	(373		)	—			—			—			(373		)
Dividends paid on L3’s common stock	(220		)	—			—			—			(220		)
Other financing activities	490			(427		)	(163		)	146			46
Net cash used in financing activities from continuing operations	(412		)	(427		)	(163		)	146			(856		)
Effect of foreign currency exchange rate changes on cash	—			—			(13		)	—			(13		)
Net increase in cash and cash equivalents of discontinued operations	13			—			—			—			13
Net increase in cash	153			5			38			(40		)	156
Cash and cash equivalents, beginning of the year	109			—			165			(67		)	207
Cash and cash equivalents, end of the year	$	262		$	5		$	203		$	(107	)	$	363

For the year ended December 31, 2015:
Operating activities:
Net cash from operating activities from continuing operations	$	633		$	428		$	159		$	(185	)	$	1,035
Investing activities:
Business acquisitions, net of cash acquired	(320		)	—			—			—			(320		)
Proceeds from sale of businesses, net of closing date cash balances	42			—			276			—			318
Other investing activities	(75		)	(78		)	(35		)	—			(188		)
Net cash (used in) from investing activities from continuing operations	(353		)	(78		)	241			—			(190		)
Financing activities:
Repurchases of senior notes	(297		)	—			—			—			(297		)
Common stock repurchased	(740		)	—			—			—			(740		)
Dividends paid on L3's common stock	(214		)	—			—			—			(214		)
Other financing activities	639			(355		)	(418		)	180			46
Net cash used in financing activities from continuing operations	(612		)	(355		)	(418		)	180			(1,205		)
Effect of foreign currency exchange rate changes on cash	—			—			(19		)	—			(19		)
Net increase in cash and cash equivalents of discontinued operations	83			—			—			—			83
Change in cash balance in assets held for sale	—			1			60			—			61
Net (decrease) increase in cash	(249		)	(4		)	23			(5		)	(235		)
Cash and cash equivalents, beginning of the year	358			4			142			(62		)	442
Cash and cash equivalents, end of the year	$	109		$	—		$	165		$	(67	)	$	207

Description of Business (Details) $ in Billions	12 Months Ended
Description of Business (Details) $ in Billions	Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments \| Segment	3
Discontinued Operations [Member] \| Vertex Aerospace [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales \| $	$ 1.4	$ 1.3	$ 1.2

Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Sep. 29, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Estimates [Abstract]
Increase in operating income due to changes in contract estimates		$ 184	$ 149	$ 52
Percentage of increase in consolidated operating income due to changes in contract estimates		18.00%	16.00%	6.00%
Increase in operating income due to changes in contract estimates, diluted (in dollars per share)		$ 1.48	$ 1.23	$ 0.45
Revenue Recognition [Abstract]
Percentage of net sales accounted for under contract accounting standards		59.00%
Percentage of fixed-price type contracts		49.00%
Percentage of cost-plus type contracts		10.00%
Period of performance for contracts accounted for under the percentage-of-completion method of accounting, minimum		1 year
Accrued product warranty costs [Roll Forward]:
Balance at January 1		$ 109	$ 105
Acquisitions during this period		3	3
Accruals for product warranties issued during the period		52	51
Foreign currency translation adjustments		1	(1)
Settlements made during the period		(66)	(49)
Balance at December 31		99	109	$ 105
Goodwill and Indefinite-lived Intangible Assets [Abstract]
Goodwill impairment charges		0	$ 0	46
NSS [Member]
Goodwill and Indefinite-lived Intangible Assets [Abstract]
Goodwill impairment charges				955
NSS [Member] \| Discontinued Operations [Member]
Goodwill and Indefinite-lived Intangible Assets [Abstract]
Goodwill impairment charges				909
NSS [Member] \| Continuing Operations [Member]
Goodwill and Indefinite-lived Intangible Assets [Abstract]
Goodwill impairment charges				$ 46
Vertex Aerospace [Member]
Goodwill and Indefinite-lived Intangible Assets [Abstract]
Goodwill impairment charges	$ 187	187
Goodwill impairment after income taxes		$ 133
Minimum [Member] \| Buildings and Improvements [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life		10 years
Minimum [Member] \| Machinery, Equipment, Furniture and Fixtures [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life		3 years
Maximum [Member] \| Buildings and Improvements [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life		40 years
Maximum [Member] \| Machinery, Equipment, Furniture and Fixtures [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life		10 years

Summary of Significant Accounting Policies, Accounting Standards Issued and Not Yet Implemented (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASU 2017-07 [Member]
Summary of Significant Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle, effect of change on operating income	$ 11	$ 1	$ 27
New Accounting pronouncement or change in accounting principle, effect of change on interest and other income, net	(11)	$ (1)	$ (27)
Accounting Standards Update 2014-09 [Member]
Summary of Significant Accounting Policies [Line Items]
Reclassification from inventory to other cost	$ 50
New accounting pronouncement or change in accounting principle effect of change on current assets, percentage	(2.00%)
New accounting pronouncement or change in accounting principle effect of change on current liabilities, percentage	(2.00%)
Accounting Standards Update 2014-09 [Member] \| Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle, cumulative effect of change on shareholders equity	$ 10
New accounting pronouncement or change in accounting principle, effect of change on net sales	350
Accounting Standards Update 2014-09 [Member] \| Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle, cumulative effect of change on shareholders equity	20
New accounting pronouncement or change in accounting principle, effect of change on net sales	$ 400

Acquisitions, Divestitures and Discontinued Operations, Business Acquisitions (Details) £ in Millions, $ in Millions														3 Months Ended								12 Months Ended
	Dec. 18, 2017 USD ($)	Oct. 17, 2017 USD ($)	Sep. 08, 2017 USD ($)	May 19, 2017 USD ($)	Jan. 05, 2017 USD ($)	Nov. 22, 2016 USD ($)	Nov. 22, 2016 GBP (£)	Sep. 30, 2016 USD ($)	Jan. 22, 2016 USD ($)	Oct. 13, 2015 USD ($)	May 27, 2015 USD ($)	May 27, 2015 GBP (£)	Jan. 21, 2015 USD ($)	Dec. 31, 2017 USD ($)	Sep. 29, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 23, 2016 USD ($)	Jun. 24, 2016 USD ($)	Mar. 25, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 12, 2017 USD ($)	Mar. 17, 2017 USD ($)	Nov. 22, 2016 GBP (£)	May 27, 2015 GBP (£)
Business Acquisition [Line Items]
Fair value of liability, contingent consideration														$ 31				$ 29				$ 31	$ 29
Goodwill recognized														6,615				6,374				6,615	6,374	$ 6,095
Net sales														$ 2,574	$ 2,293	$ 2,385	$ 2,321	$ 2,643	$ 2,184	$ 2,318	$ 2,065	9,573	9,210	9,231
Loss before income taxes																						871	$ 804	$ 639
Kigre, Inc [Member]
Business Acquisition [Line Items]
Purchase price of acquisition	$ 13
Goodwill recognized	$ 9
Escola De Aviacao Aerocondor, S.A [Member]
Business Acquisition [Line Items]
Purchase price of acquisition		$ 13
Goodwill recognized		$ 12
Doss Aviation, Inc. [Member]
Business Acquisition [Line Items]
Goodwill recognized																									$ 37
Goodwill deductible for income tax purposes																									$ 13
Adaptive Methods, Inc. [Member]
Business Acquisition [Line Items]
Purchase price of acquisition			$ 33
Goodwill recognized			$ 28
OpenWaterPowerInc [Member]
Business Acquisition [Line Items]
Fair value of liability, contingent consideration				$ 14
Goodwill recognized				25
OpenWaterPowerInc [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Purchase price of acquisition				17
OpenWaterPowerInc [Member] \| IPR&D [Member]
Business Acquisition [Line Items]
Identifiable intangible assets				$ 65
OceanServer Technology, Inc. [Member]
Business Acquisition [Line Items]
Goodwill recognized																										$ 19
Explosive Trace Detection Business of Implant Sciences [Member]
Business Acquisition [Line Items]
Purchase price of acquisition					$ 118
Goodwill recognized					$ 80
Kigre, G-Air, Doss Aviation, Adaptive Methods, Open Water Power, OceanServer and ETD Business [Member]
Business Acquisition [Line Items]
Net sales																						80
Loss before income taxes																						$ (1)
MacDonald Humfrey (Automation) Limited [Member]
Business Acquisition [Line Items]
Purchase price of acquisition						$ 327	£ 263
Fair value of liability, contingent consideration						26																					£ 21
Goodwill recognized						255																					204
Identifiable intangible assets						$ 56																					45
Weighted average useful life						10 years	10 years
MacDonald Humfrey (Automation) Limited [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Business acquisition contingent consideration						$ 38																					30
MacDonald Humfrey (Automation) Limited [Member] \| Trade Names [Member]
Business Acquisition [Line Items]
Identifiable intangible assets						8																					6
MacDonald Humfrey (Automation) Limited [Member] \| Technology [Member]
Business Acquisition [Line Items]
Identifiable intangible assets						12																					10
MacDonald Humfrey (Automation) Limited [Member] \| Customer Relationships [Member]
Business Acquisition [Line Items]
Identifiable intangible assets						$ 36																					£ 29
Micreo Limited and Aerosim [Member]
Business Acquisition [Line Items]
Purchase price of acquisition								$ 86
Goodwill recognized								59
Goodwill deductible for income tax purposes								$ 6
Advanced Technical Materials, Inc. [Member]
Business Acquisition [Line Items]
Purchase price of acquisition									$ 27
Goodwill recognized									$ 20
ForceX, Inc. [Member]
Business Acquisition [Line Items]
Purchase price of acquisition										$ 61
Goodwill recognized										53
Goodwill deductible for income tax purposes										$ 52
CTC Aviation Group [Member]
Business Acquisition [Line Items]
Purchase price of acquisition											$ 236	£ 153
Goodwill recognized											$ 182																	£ 118
MITEQ, Inc. [Member]
Business Acquisition [Line Items]
Purchase price of acquisition													$ 41
Goodwill recognized													11
Goodwill deductible for income tax purposes													$ 4

Acquisitions, Divestitures and Discontinued Operations, Unaudited Pro Forma Statements of Operations Data (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Business Combinations [Abstract]
Pro forma net sales	$ 9,638	$ 9,493
Pro forma income from continuing operations attributable to L3	753	621
Pro forma net income attributable to L3	$ 677	$ 712
Pro forma diluted earnings per share from continuing operations (in dollars per share)	$ 9.46	$ 7.88
Pro forma diluted earnings per share (in dollars per share)	$ 8.51	$ 9.03

Acquisitions, Divestitures and Discontinued Operations, Business Divestitures (Details) € in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 29, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 23, 2016 USD ($)	Jun. 24, 2016 USD ($)	Mar. 25, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 01, 2017 USD ($)	Mar. 01, 2017 EUR (€)	Feb. 24, 2017 USD ($)	Feb. 23, 2017 USD ($)	Jul. 27, 2015 USD ($)	May 29, 2015 USD ($)	May 29, 2015 EUR (€)	Apr. 24, 2015 USD ($)
Business Divestiture [Abstract]
(Loss) gain related to business divestitures									$ 0	$ 0	$ (31)
Proceeds received											358
Net sales											209
Net sales	$ 2,574	$ 2,293	$ 2,385	$ 2,321	$ 2,643	$ 2,184	$ 2,318	$ 2,065	9,573	9,210	9,231
Income from continuing operations before income taxes									871	804	639
Income (Loss) from Continuing Operations [Member]
Business Divestiture [Abstract]
(Loss) gain related to business divestitures									(4)
Proceeds received									25
Net sales									10
Discontinued Operations [Member]
Business Divestiture [Abstract]
Net sales									10	59	259
Income from continuing operations before income taxes									2	$ 8	8
Aviation Jet Services Divestiture [Member]
Business Divestiture [Abstract]
(Loss) gain related to business divestitures									(5)
Proceeds received									1
Net sales									1
Sale of business, sale price												$ 1	€ 1
Coleman Divestiture [Member]
Business Divestiture [Abstract]
(Loss) gain related to business divestitures									(3)
Proceeds received									17
Net sales									9
Sale of business, sale price														$ 15
Display Product Line Divestiture [Member]
Business Divestiture [Abstract]
(Loss) gain related to business divestitures									4
Proceeds received									7
Net sales									$ 0
Sale of business, sale price															$ 7
MSI Divestiture [Member]
Business Divestiture [Abstract]
(Loss) gain related to business divestitures											(17)
Proceeds received											318
Net sales											185
Sale of business, sale price																	$ 318	€ 295
Estimated employee pension related liabilities \| €																		€ 60
BSI Divestiture [Member]
Business Divestiture [Abstract]
(Loss) gain related to business divestitures											(4)
Proceeds received											26
Net sales											7
Sale of business, sale price																			$ 26
Tinsley Product Line Divestiture [Member]
Business Divestiture [Abstract]
(Loss) gain related to business divestitures											(8)
Proceeds received											4
Net sales											9
Sale of business, sale price																$ 4
Klein Divestiture [Member]
Business Divestiture [Abstract]
(Loss) gain related to business divestitures											(2)
Proceeds received											10
Net sales											8
Sale of business, sale price											$ 10

Acquisitions, Divestitures and Discontinued Operations, Discontinued Operations (Details) - USD ($) $ in Millions		12 Months Ended
	Feb. 01, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Discontinued Operations [Abstract]
Proceeds from sale of discontinued operations				$ 358
Net sales				209
(Loss) income from discontinued operations net of income taxes		$ (76)	$ 91	(732)
Gain (loss) related to business divestitures		0	0	(31)
Assets [Abstract]
Current assets		306	481	1,124
Liabilities [Abstract]
Current liabilities		226	235
Vertex Aerospace [Member] \| Discontinued Operations [Member]
Discontinued Operations [Abstract]
Net sales		1,400	1,300	1,200
Goodwill impairment charges				338
Assets [Abstract]
Current assets		284	271
Property, plant and equipment, net		13	14
Goodwill		0	187
Other Intangible Assets		7	9
Other assets		2	0
Total assets of discontinued operations		306	481
Liabilities [Abstract]
Accounts payable, trade		63	16
Other current liabilities		131	160
Current liabilities		194	176
Long-term liabilities		32	59
Total liabilities of discontinued operations		226	235
NSS [Member] \| Discontinued Operations [Member]
Discontinued Operations [Abstract]
Goodwill impairment charges				571
Gain (loss) related to business divestitures			64
Trailing expenses related to sale		1
NSS [Member] \| Discontinued Operations [Member] \| CACI International Inc [Member]
Discontinued Operations [Abstract]
Proceeds from sale of discontinued operations	$ 547
Vertex Aerospace and NSS [Member] \| Discontinued Operations [Member]
Discontinued Operations [Abstract]
Net sales		1,429	1,402	2,334
Cost of sales		(1,342)	(1,357)	(2,259)
(Loss) gain related to business divestiture		(1)	64	0
Goodwill impairment charges		187	0	909
Operating (loss) income from discontinued operations		(101)	109	(834)
Interest expense allocated to discontinued operations		(2)	(5)	(26)
(Loss) income from discontinued operations before income taxes		(103)	104	(860)
Income tax benefit (expense)		27	(13)	128
(Loss) income from discontinued operations net of income taxes		$ (76)	$ 91	$ (732)

Acquisitions, Divestitures and Discontinued Operations, Assets Held for Sale (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets [Abstract]
Total current assets	$ 306	$ 481	$ 1,124
Liabilities [Abstract]
Current liabilities	226	$ 235
Discontinued Operations, Held-for-sale [Member]
Assets [Abstract]
Billed receivables	14
Contracts in process	33
Total current assets	47
Property, plant and equipment, net	34
Goodwill	52
Indentifiable intangible assets	2
Total assets of discontinued operations	135
Liabilities [Abstract]
Accounts payable, trade	3
Accrued employment costs	2
Accrued expenses	3
Other current liabilities	5
Current liabilities	13
Deferred income taxes	4
Total liabilities of discontinued operations	$ 17

Contracts in Process (Details) - USD ($) $ in Millions	12 Months Ended
Contracts in Process (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Contracts Receivable [Abstract]
Unbilled contract receivables, gross	$ 1,874	$ 1,890
Unliquidated progress payments	(761)	(827)
Unbilled contract receivables, net	1,113	1,063
Inventoried contract costs, gross	891	998
Unliquidated progress payments	(71)	(203)
Inventoried contract costs, net	820	795
Total contracts in process	$ 1,933	1,858
Percentage of unbilled contract receivables, net billed and collected within one year	92.00%
Contracts Receivable [Line Items]
Percentage of incurred costs billed	80.00%
Severance and restructuring costs	$ 91	13	$ 14
Summary Of Inventory For Long Term Contracts Or Programs [Roll Forward]
Amounts included in inventoried contract costs at beginning of the year	173	137	114
Contract costs incurred [Abstract]:
IRAD and B&P	333	304	280
Other G&A	842	749	742
Total	1,175	1,053	1,022
Amounts charged to cost of sales	(1,179)	(1,017)	(999)
Amounts included in inventoried contract costs at end of the year	169	173	137
Operating Expenses [Abstract]
Selling, general and administrative expenses	278	223	261
Research and development expenses	63	54	52
Total	$ 341	$ 277	$ 313
Maximum [Member]
Contracts Receivable [Line Items]
Number of years for billed and collected, unbilled contract receivables	1 year

Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials, components and sub-assemblies	$ 184	$ 165
Work in process	98	106
Finished goods	107	59
Total	$ 389	$ 330

Goodwill and Identifiable Intangible Assets, Allocated by Reportable Segment (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) Employee	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Goodwill [Line Items]
Approximate number of employees \| Employee	31,000
Goodwill [Roll Forward]
Goodwill	$ 6,719	$ 6,478	$ 6,199
Accumulated impairment losses	(104)	(104)	(104)
Balance, Beginning	6,374	6,095
Business acquisitions	212	335
Business divestitures	(12)
Foreign currency translation adjustments	93	(56)
Assets held for sale	(52)
Balance, Ending	6,615	6,374
ISRS [Member]
Goodwill [Roll Forward]
Goodwill	2,504	2,512	2,493
Accumulated impairment losses	(46)	(46)	(46)
Balance, Beginning	2,466	2,447
Business acquisitions	8	28
Business divestitures	0
Foreign currency translation adjustments	26	(9)
Assets held for sale	(42)
Balance, Ending	2,458	2,466
C&NS [Member]
Goodwill [Roll Forward]
Goodwill	1,977	1,883	1,860
Accumulated impairment losses	(15)	(15)	(15)
Balance, Beginning	1,868	1,845
Business acquisitions	73	20
Business divestitures	0
Foreign currency translation adjustments	21	3
Assets held for sale	0
Balance, Ending	1,962	1,868
Electronic Systems [Member]
Goodwill [Roll Forward]
Goodwill	2,238	2,083	1,846
Accumulated impairment losses	(43)	(43)	$ (43)
Balance, Beginning	2,040	1,803
Business acquisitions	131	287
Business divestitures	(12)
Foreign currency translation adjustments	46	(50)
Assets held for sale	(10)
Balance, Ending	$ 2,195	$ 2,040

Goodwill and Identifiable Intangible Assets, Identifiable Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite-lived intangible assets, gross carrying amount	$ 611	$ 572
Finite-lived intangible assets, accumulated amortization	385	343
Net carrying amount	226	229
Amortization expense	43	33	$ 32
Estimated Amortization Expense for Identifiable Intangible Assets [Abstract]
Estimated amortization expense, 2018	44
Estimated amortization expense, 2019	39
Estimated amortization expense, 2020	31
Estimated amortization expense, 2021	25
Estimated amortization expense, 2022	21
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	677	572
Intangible assets, net carrying amount	292	229
IPR&D [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 66	0
Customer Contractual Relationships [Member]
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite lived intangible assets, weighted average amortization period	14 years
Finite-lived intangible assets, gross carrying amount	$ 393	360
Finite-lived intangible assets, accumulated amortization	257	229
Net carrying amount	$ 136	131
Technology [Member]
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite lived intangible assets, weighted average amortization period	10 years
Finite-lived intangible assets, gross carrying amount	$ 189	191
Finite-lived intangible assets, accumulated amortization	114	102
Net carrying amount	$ 75	89
Other [Member]
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite lived intangible assets, weighted average amortization period	15 years
Finite-lived intangible assets, gross carrying amount	$ 29	21
Finite-lived intangible assets, accumulated amortization	14	12
Net carrying amount	$ 15	$ 9

Other Current Liabilities and Other Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Current Liabilities [Abstract]
Accrued product warranty costs	$ 69	$ 68
Estimated costs in excess of estimated contract value to complete contracts in process in a loss position	63	70
Accrued interest	43	43
Deferred revenues	38	34
Estimated contingent purchase price payable for acquired businesses (see Note 3)	11	0
Accruals for pending and threatened litigation	3	14
Other	140	163
Total other current liabilities	367	392
Other Liabilities [Abstract]
Non-current income taxes payable (see Note 16)	164	121
Deferred compensation	49	47
Accrued product warranty costs	30	41
Accrued workers' compensation	23	25
Estimated contingent purchase price payable for acquired businesses (see Note 3)	20	29
Notes payable and capital lease obligations	16	10
Other	96	83
Total other liabilities	$ 398	$ 356

Property, Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Land	$ 34	$ 53
Buildings and improvements	404	437
Machinery, equipment, furniture and fixtures	1,959	1,857
Leasehold improvements	376	337
Gross property, plant and equipment	2,773	2,684
Accumulated depreciation and amortization	(1,663)	(1,577)
Property, plant and equipment, net	$ 1,110	$ 1,107

Debt, Components of Debt and Reconciliation to Carrying Amount of Current and Long-Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 31, 2016
Components of Debt [Abstract]
Repayments under the credit facility	$ 1,328	$ 819	$ 1,194
Proceeds under the credit facility	1,328	819	$ 1,194
Available borrowings under credit facility	1,000
3.95% Senior Notes due 2016 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt	200
5.20% Senior Notes due 2019 [Member]
Components of Debt [Abstract]
Unamortized discounts	(4)
4.75% Senior Notes due 2020 [Member]
Components of Debt [Abstract]
Unamortized discounts	(3)
4.95% Senior Notes due 2021 [Member]
Components of Debt [Abstract]
Unamortized discounts	(4)
3.95% Senior Notes due 2024 [Member]
Components of Debt [Abstract]
Unamortized discounts	(3)
3.85% Senior Notes due 2026 [Member]
Components of Debt [Abstract]
Unamortized discounts	$ (3)
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Revolving credit facility expiration period	5 years
Total aggregate borrowings under revolving credit facility				$ 1,000
Revolving credit facility expiration date	Oct. 31, 2021
Uncommitted incremental revolving facilities and additional term loan facilities				$ 600
Revolving Credit Facility [Member] \| Federal Funds Rate [Member] \| Minimum [Member]
Line of Credit Facility [Abstract]
Applicable spread on base rate	0.125%
Revolving Credit Facility [Member] \| Federal Funds Rate [Member] \| Maximum [Member]
Line of Credit Facility [Abstract]
Applicable spread on base rate	1.00%
Revolving Credit Facility [Member] \| Eurodollar [Member] \| Minimum [Member]
Line of Credit Facility [Abstract]
Applicable spread on base rate	1.125%
Revolving Credit Facility [Member] \| Eurodollar [Member] \| Maximum [Member]
Line of Credit Facility [Abstract]
Applicable spread on base rate	2.00%
L3 Technologies [Member]
Components of Debt [Abstract]
Borrowings under Revolving Credit Facility	$ 0	0
Principal amount of long-term debt	3,350	3,350
Unamortized discounts	(7)	(8)
Deferred debt issue costs	(13)	(17)
Carrying amount of long-term debt	$ 3,330	3,325
L3 Technologies [Member] \| 3.95% Senior Notes due 2016 [Member]
Components of Debt [Abstract]
Interest rate on senior notes	3.95%
L3 Technologies [Member] \| 1.50% Senior Notes due 2017 [Member]
Components of Debt [Abstract]
Interest rate on senior notes	1.50%
L3 Technologies [Member] \| 5.20% Senior Notes due 2019 [Member]
Components of Debt [Abstract]
Borrowings under Revolving Credit Facility	$ 1,000	1,000
Interest rate on senior notes	5.20%
Debt instrument maturity period	2019
L3 Technologies [Member] \| 4.75% Senior Notes due 2020 [Member]
Components of Debt [Abstract]
Borrowings under Revolving Credit Facility	$ 800	800
Interest rate on senior notes	4.75%
Debt instrument maturity period	2020
L3 Technologies [Member] \| 4.95% Senior Notes due 2021 [Member]
Components of Debt [Abstract]
Borrowings under Revolving Credit Facility	$ 650	650
Interest rate on senior notes	4.95%
Debt instrument maturity period	2021
L3 Technologies [Member] \| 3.95% Senior Notes due 2024 [Member]
Components of Debt [Abstract]
Borrowings under Revolving Credit Facility	$ 350	350
Interest rate on senior notes	3.95%
Debt instrument maturity period	2024
L3 Technologies [Member] \| 3.85% Senior Notes due 2026 [Member]
Components of Debt [Abstract]
Borrowings under Revolving Credit Facility	$ 550	550
Interest rate on senior notes	3.85%
Debt instrument maturity period	2026
L3 Technologies [Member] \| Revolving Credit Facility [Member]
Components of Debt [Abstract]
Repayments under the credit facility	$ 1,328
Proceeds under the credit facility	1,328
Available borrowings under credit facility	$ 1,000	$ 1,000

Debt, Outstanding Senior Subordinated Notes (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Debt Instruments [Abstract]

Net Cash Proceeds

$ 0

$ 547

$ 0

Senior Notes Redemption [Abstract]

Debt Retirement Charge

(7)

(1)

Cash payments of senior notes

$ 0

856

297

3.95% Senior Notes due 2016 [Member]

Debt Instruments [Abstract]

Redemption price as percentage of principal amount

101.475%

Senior Notes due

Nov. 15, 2016

Senior Notes Redemption [Abstract]

Redemption Date

^[1]

May 20, 2016

Maturity date

Nov. 15, 2016

Redemption amount

$ 300

Principal Amount

200

Debt Retirement Charge

Redemption cash payments

305

Cash payments of senior notes

$ 200

1.50% Senior Notes due 2017 [Member]

Debt Instruments [Abstract]

Redemption price as percentage of principal amount

100.323%

Senior Notes Redemption [Abstract]

Redemption Date

^[2]

Dec. 30, 2016

Redemption amount

$ 350

Debt Retirement Charge

Redemption cash payments

$ 351

5.20% Senior Notes due 2019 [Member]

Debt Instruments [Abstract]

Oct. 02, 2009

$ 1,000

$ 987

Effective Interest Rate

5.25%

Redemption at Treasury Rate

30.00%

4.75% Senior Notes due 2020 [Member]

Debt Instruments [Abstract]

May 21, 2010

$ 800

$ 790

Effective Interest Rate

4.79%

Redemption at Treasury Rate

25.00%

4.95% Senior Notes due 2021 [Member]

Debt Instruments [Abstract]

Feb. 07, 2011

$ 650

$ 639

Effective Interest Rate

5.02%

Redemption at Treasury Rate

25.00%

Senior Notes due

Nov. 15, 2020

Senior Notes Redemption [Abstract]

Maturity date

Nov. 15, 2020

3.95% Senior Notes due 2024 [Member]

Debt Instruments [Abstract]

May 28, 2014

$ 650

$ 641

Effective Interest Rate

4.02%

Redemption at Treasury Rate

20.00%

Senior Notes Redemption [Abstract]

Tender date

Dec. 22, 2015

Tender amount

$ 300

Debt Retirement Charge

Tender cash payments

$ 297

3.85% Senior Notes due 2026 [Member]

Debt Instruments [Abstract]

Dec. 05, 2016

$ 550

$ 542

Effective Interest Rate

3.91%

Redemption at Treasury Rate

25.00%

L3 Technologies [Member]

Debt Instruments [Abstract]

Discount

$ 7

Net Cash Proceeds

547

Redemption price as percentage of principal amount

101.00%

Senior Notes Redemption [Abstract]

Principal Amount

$ 3,350

3,350

Debt Retirement Charge

(7)

(1)

Cash payments of senior notes

$ 856

$ 297

L3 Technologies [Member] | Minimum [Member]

Debt Instruments [Abstract]

Redemption price as percentage of principal amount

100.00%

L3 Technologies [Member] | 3.95% Senior Notes due 2016 [Member]

Debt Instruments [Abstract]

Interest rate on senior notes

3.95%

L3 Technologies [Member] | 1.50% Senior Notes due 2017 [Member]

Debt Instruments [Abstract]

Interest rate on senior notes

1.50%

L3 Technologies [Member] | 5.20% Senior Notes due 2019 [Member]

Debt Instruments [Abstract]

Interest rate on senior notes

5.20%

L3 Technologies [Member] | 4.75% Senior Notes due 2020 [Member]

Debt Instruments [Abstract]

Interest rate on senior notes

4.75%

L3 Technologies [Member] | 4.95% Senior Notes due 2021 [Member]

Debt Instruments [Abstract]

Interest rate on senior notes

4.95%

L3 Technologies [Member] | 3.95% Senior Notes due 2024 [Member]

Debt Instruments [Abstract]

Interest rate on senior notes

3.95%

L3 Technologies [Member] | 3.95% Senior Notes due 2024 [Member] | Minimum [Member]

Debt Instruments [Abstract]

Senior Notes due

Feb. 28, 2024

Senior Notes Redemption [Abstract]

Maturity date

Feb. 28, 2024

L3 Technologies [Member] | 3.85% Senior Notes due 2026 [Member]

Debt Instruments [Abstract]

Interest rate on senior notes

3.85%

L3 Technologies [Member] | 3.85% Senior Notes due 2026 [Member] | Minimum [Member]

Debt Instruments [Abstract]

Senior Notes due

Sep. 15, 2026

Senior Notes Redemption [Abstract]

Maturity date

Sep. 15, 2026

[1]	The 3.95% Senior Notes due 2016 were redeemed at a price equal to 101.475% of the principal amount thereof, plus accrued and unpaid interest. Interest ceased to accrue on and after May 20, 2016, and the only remaining right of holders of such Notes was to receive payment of the redemption price and accrued interest.
[2]	The 1.50% Senior Notes due 2017 were redeemed at a price equal to 100.323% of the principal amount thereof, plus accrued and unpaid interest to the redemption date. Interest ceased to accrue on and after the redemption date.

Debt, Guarantees and Covenants (Details) - L3 Technologies [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Ownership percentage	100.00%
Minimum consolidated interest coverage ratio under revolving credit facility covenants	300.00%
Minimum consolidated senior leverage ratio under revolving credit facility covenants	375.00%
Maximum consolidated senior leverage ratio under revolving credit facility covenants	400.00%
Minimum aggregate amount of indebtedness, swap contracts or guarantees to trigger cross default provisions	$ 75
Maximum days to cure defaults triggering cross default provisions	10 days
Minimum aggregate amount of senior notes accelerated to trigger cross default provisions	$ 100

Accumulated Other Comprehensive (Loss) Income (AOCI), Summary of AOCI Balances Including Amounts Reclassified from AOCI into Net Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	$ 4,553
Other comprehensive (loss) income before reclassifications, net of tax	(6)	$ (193)	$ (95)
Amounts reclassified from AOCI, net of tax	41	41	105
Net current period other comprehensive (loss) income	35	(152)	10
Ending Balance	5,083	4,553
Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(726)	(574)	(584)
Ending Balance	(691)	(726)	(574)
Foreign Currency Translation Adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(178)	(101)	19
Other comprehensive (loss) income before reclassifications, net of tax	124	(77)	(161)
Amounts reclassified from AOCI, net of tax	0	0	41
Net current period other comprehensive (loss) income	124	(77)	(120)
Ending Balance	(54)	(178)	(101)
Unrealized (Losses) Gains on Hedging Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	6	(8)	(5)
Other comprehensive (loss) income before reclassifications, net of tax	7	3	(15)
Amounts reclassified from AOCI, net of tax	(4)	11	12
Net current period other comprehensive (loss) income	3	14	(3)
Ending Balance	9	6	(8)
Unrecognized (Losses) Gains and Prior Service Cost, Net [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(554)	(465)	(598)
Other comprehensive (loss) income before reclassifications, net of tax	(137)	(119)	81
Amounts reclassified from AOCI, net of tax	45	30	52
Net current period other comprehensive (loss) income	(92)	(89)	133
Ending Balance	$ (646)	$ (554)	$ (465)

Accumulated Other Comprehensive (Loss) Income (AOCI), Summary of Amounts Reclassified from AOCI into Net Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Loss related to business divestitures									$ 0	$ 0	$ 31
Cost of sales-products									(5,991)	(5,817)	(6,016)
Income from continuing operations before income taxes									871	804	639
Provision for income taxes									(102)	(171)	(132)
Income from continuing operations	$ 271	$ 146	$ 195	$ 157	$ 187	$ 149	$ 134	$ 163	769	633	507
MSI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Loss related to business divestitures											17
Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations									(41)	(41)	(105)
Foreign Currency Translation Adjustments [Member] \| Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations before income taxes									0	0	(41)
Income from continuing operations									0	0	(41)
Foreign Currency Translation Adjustments [Member] \| Amount Reclassified from AOCI [Member] \| MSI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Loss related to business divestitures									0	0	41
Losses on Hedging Instruments [Member] \| Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales-products									5	(13)	(16)
Income from continuing operations before income taxes									5	(13)	(18)
Provision for income taxes									(1)	2	6
Income from continuing operations									4	(11)	(12)
Losses on Hedging Instruments [Member] \| Amount Reclassified from AOCI [Member] \| MSI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Loss related to business divestitures									0	0	2
Amortization of Defined Benefit Pension Items [Member] \| Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net loss									(59)	(48)	(67)
Income from continuing operations before income taxes									(59)	(48)	(81)
Provision for income taxes									14	18	29
Income from continuing operations									(45)	(30)	(52)
Amortization of Defined Benefit Pension Items [Member] \| Amount Reclassified from AOCI [Member] \| MSI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Loss related to business divestitures									$ 0	$ 0	$ 14

Equity (Details) - USD ($) $ / shares in Units, $ in Millions		2 Months Ended	12 Months Ended
	Feb. 12, 2018	Feb. 16, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 08, 2017	Dec. 04, 2014
Class of Stock [Line Items]
Aggregate amount of repurchased shares			$ 180	$ 373	$ 740
Cash dividends declared per common share (in dollars per share)			$ 3	$ 2.8	$ 2.6
Cash dividends			$ 236	$ 220	$ 213
Subsequent Event [Member]
Class of Stock [Line Items]
Average price per share of repurchased shares (in dollars per share)		$ 203.33
Aggregate amount of repurchased shares		$ 88
Cash dividends declared per common share (in dollars per share)	$ 0.80
Dividend declared date	Feb. 12, 2018
Dividend paid date	Mar. 15, 2018
Dividend paid, record date	Mar. 01, 2018
Treasury Stock [Member]
Class of Stock [Line Items]
Aggregate amount of repurchased shares			$ 180	$ 373	$ 740
Share Repurchase Program December 4, 2014 [Member]
Class of Stock [Line Items]
Amount of shares authorized to be repurchased							$ 1,500
Share Repurchase Program December 4, 2014 [Member] \| Subsequent Event [Member]
Class of Stock [Line Items]
Number of common shares repurchased (in shares)		433,039
Share Repurchase Program December 4, 2014 [Member] \| Treasury Stock [Member]
Class of Stock [Line Items]
Number of common shares repurchased (in shares)			1,000,000
Average price per share of repurchased shares (in dollars per share)			$ 183.67
Aggregate amount of repurchased shares			$ 180
Share Repurchase Program May 8, 2017 [Member]
Class of Stock [Line Items]
Amount of shares authorized to be repurchased						$ 1,500

Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Liabilities [Abstract]
Contingent consideration	$ 29	$ 31	$ 29
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	29
Acquisitions	14
Changes in fair value of contingent consideration, net	(12)
Balance at end of period	31
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Assets [Abstract]
Cash equivalents		310	104
Derivatives (foreign currency forward contracts)		0	0
Total assets		310	104
Liabilities [Abstract]
Derivatives (foreign currency forward contracts)		0	0
Contingent consideration	0	0	0
Total liabilities		0	0
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	0
Balance at end of period	0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Assets [Abstract]
Cash equivalents		0	0
Derivatives (foreign currency forward contracts)		11	12
Total assets		11	12
Liabilities [Abstract]
Derivatives (foreign currency forward contracts)		1	6
Contingent consideration	0	0	0
Total liabilities		1	6
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	0
Balance at end of period	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member]
Assets [Abstract]
Cash equivalents		0	0
Derivatives (foreign currency forward contracts)		0	0
Total assets		0	0
Liabilities [Abstract]
Derivatives (foreign currency forward contracts)		0	0
Contingent consideration	29	31	29
Total liabilities		$ 31	$ 29
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	29
Balance at end of period	$ 31

Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes	$ 3,330	$ 3,325
Foreign currency forward contracts	10	6
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes	3,502	3,526
Foreign currency forward contracts	$ 10	$ 6

Derivative Financial Instruments, Outstanding Forward Contracts By Currency (Details) - Foreign Currency Forward Contracts [Member] $ in Millions	Dec. 31, 2017 USD ($)
Derivative [Line Items]
Notional amount	$ 307
U.S. Dollar [Member]
Derivative [Line Items]
Notional amount	108
Canadian Dollar [Member]
Derivative [Line Items]
Notional amount	100
Euro [Member]
Derivative [Line Items]
Notional amount	84
British Pound [Member]
Derivative [Line Items]
Notional amount	$ 15

Derivative Financial Instruments, Fair Value on Consolidated Balance Sheet (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Realized pre-tax gain (loss) on forward contract	$ 5	$ (13)	$ (18)
Estimated net amount of existing gains expected to be reclassified into income within the next 12 months	2
Other Current Assets [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	11	10
Other Current Assets [Member] \| Foreign Currency Forward Contracts [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	11	10
Other Assets [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	0	2
Other Assets [Member] \| Foreign Currency Forward Contracts [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	0	2
Other Current Liabilities [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	1	6
Other Current Liabilities [Member] \| Foreign Currency Forward Contracts [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	1	6
Other Liabilities [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	0	0
Other Liabilities [Member] \| Foreign Currency Forward Contracts [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	$ 0	$ 0

L3's Earnings Per Share, Reconciliation of Basic and Diluted Earnings Per Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of net income (loss) [Abstract]
Net income (loss)	$ 293	$ 25	$ 207	$ 168	$ 192	$ 151	$ 151	$ 230	$ 693	$ 724	$ (225)
Net income from continuing operations attributable to noncontrolling interests									(16)	(14)	(15)
Net income (loss) attributable to L-3	289	22	202	164	188	148	147	227	677	710	(240)
Earnings (loss) attributable to L3's common shareholders: [Abstract]
Continuing operations									753	619	492
Discontinued operations, net of income tax									(76)	91	(732)
Net income (loss) attributable to L-3	$ 289	$ 22	$ 202	$ 164	$ 188	$ 148	$ 147	$ 227	$ 677	$ 710	$ (240)
Basic [Abstract]
Weighted average common shares outstanding (in shares)									78.0	77.4	80.7
Basic earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	$ 3.42	$ 1.83	$ 2.44	$ 1.97	$ 2.37	$ 1.89	$ 1.68	$ 2.06	$ 9.65	$ 7.99	$ 6.10
Discontinued operations, net of income tax (in dollars per share)									(0.97)	1.18	(9.07)
Basic earnings (loss) per share (in dollars per share)	3.70	0.28	2.59	2.11	2.43	1.91	1.90	2.92	$ 8.68	$ 9.17	$ (2.97)
Common and potential common shares [Abstract]
Weighted average common shares outstanding (in shares)									78.0	77.4	80.7
Effect of dilutive securities									1.6	1.4	1.2
Common and potential common shares (in shares)									79.6	78.8	81.9
Diluted earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	3.34	1.79	2.39	1.93	2.32	1.85	1.66	2.02	$ 9.46	$ 7.86	$ 6.01
Discontinued operations, net of income tax (in dollars per share)									(0.95)	1.15	(8.94)
Diluted earnings (loss) per share (in dollars per share)	$ 3.62	$ 0.28	$ 2.54	$ 2.07	$ 2.38	$ 1.88	$ 1.88	$ 2.87	$ 8.51	$ 9.01	$ (2.93)

L3's Earnings Per Share (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Shares excluded from computation of diluted earnings per share (in shares)	0.3	0.4	0.6

Income Taxes, Income from Continuing Operations Before Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Federal corporate tax rate			35.00%	35.00%	35.00%
Estimated tax benefit amount	$ (79)		$ (79)
Benefit amount from remeasurement of deferred tax assets			(101)
Estimated toll charge			22
Domestic			649	$ 608	$ 509
Foreign			222	196	130
Income from continuing operations before income taxes			$ 871	$ 804	$ 639
Subsequent Event [Member]
Income Tax Disclosure [Line Items]
Federal corporate tax rate		21.00%

Income Taxes, Components of Current and Deferred Portions of Provision for Income Taxes on Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current income tax provision [Abstract]
Federal	$ 44	$ 88	$ 81
State and local	10	8	7
Foreign	56	48	26
Subtotal	110	144	114
Deferred income tax provision/(benefit) [Abstract]
Federal	(16)	25	9
State and local	6	2	7
Foreign	2	0	2
Subtotal	(8)	27	18
Total provision for income taxes	$ 102	$ 171	$ 132

Income Taxes, Reconciliation of Statutory Federal Income Tax Rate to Effective Income Tax Rate on Continuing Operations (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	35.00%	35.00%	35.00%
State and local income taxes, net of federal income tax benefit	2.00%	2.00%	2.00%
Foreign income taxes	(6.70%)	(3.00%)	(7.10%)
Manufacturing benefits	(1.40%)	(2.20%)	(2.20%)
Research and experimentation and other tax credits	(4.10%)	(4.60%)	(6.50%)
Resolution of tax contingencies	(0.40%)	(3.10%)	(1.40%)
Tax deductible dividends	(0.90%)	(1.00%)	(1.20%)
Equity compensation - excess income tax benefits	(2.30%)	(2.10%)	0.00%
Goodwill impairment	0.00%	0.00%	1.90%
Tax Reform	(9.10%)	0.00%	0.00%
Other, net	(0.40%)	0.30%	0.20%
Effective income tax rate on continuing operations	11.70%	21.30%	20.70%

Income Taxes, Components of Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets [Abstract]
Inventoried costs	$ 44	$ 53
Compensation and benefits	94	139
Pension and postretirement benefits	281	413
Loss carryforwards	12	19
Tax credit carryforwards	5	6
Other	57	87
Deferred tax assets	493	717
Less: valuation allowance	(10)	(12)
Deferred tax assets, net of valuation allowance	483	705
Deferred tax liabilities [Abstract]
Goodwill and other intangible assets	(514)	(722)
Income recognition on contracts in process	(24)	(22)
Property, plant and equipment	(59)	(93)
Other	(41)	(55)
Deferred tax liabilities	(638)	(892)
Total deferred tax liabilities, net of valuation allowance	$ (155)	$ (187)

Income Taxes, Classification of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Non-current deferred tax assets	$ 3	$ 2
Non-current deferred tax liabilities	(158)	(189)
Total deferred tax liabilities, net of valuation allowance	$ (155)	$ (187)

Income Taxes, Summary of Loss and Tax Credit Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Tax Credit Carryforward [Line Items]
Capital loss carryforwards, Tax Effected	$ 12	$ 19
Capital loss carryforwards, Valuation Allowance, Tax Effected	(10)	(12)
Total loss carryforwards, Tax Effected	12
Tax credit carryforwards, Tax Effected	5	$ 6
Total loss carryforwards, Valuation Allowance Tax Effected	(5)
Tax credit carryforwards, Valuation Allowances Tax Effected	(4)
Federal [Member]
Tax Credit Carryforward [Line Items]
Capital loss carryforwards, Gross	29
Capital loss carryforwards, Tax Effected	6
Capital loss carryforwards, Valuation Allowance, Gross	(5)
Capital loss carryforwards, Valuation Allowance, Tax Effected	$ (1)
Federal [Member] \| Minimum [Member]
Tax Credit Carryforward [Line Items]
Capital loss carryforwards, Expiration Period	2026
Federal [Member] \| Maximum [Member]
Tax Credit Carryforward [Line Items]
Capital loss carryforwards, Expiration Period	2036
Foreign [Member]
Tax Credit Carryforward [Line Items]
Capital loss carryforwards, Gross	$ 12
Capital loss carryforwards, Tax Effected	3
Capital loss carryforwards, Valuation Allowance, Gross	(6)
Capital loss carryforwards, Valuation Allowance, Tax Effected	(2)
State [Member]
Tax Credit Carryforward [Line Items]
Capital loss carryforwards, Gross	160
Capital loss carryforwards, Tax Effected	3
Capital loss carryforwards, Valuation Allowance, Gross	(135)
Capital loss carryforwards, Valuation Allowance, Tax Effected	(2)
Tax credit carryforwards, Tax Effected	5
Tax credit carryforwards, Gross	6
Tax credit carryforwards, Valuation Allowances Gross	(5)
Tax credit carryforwards, Valuation Allowances Tax Effected	$ (4)
State [Member] \| Minimum [Member]
Tax Credit Carryforward [Line Items]
Capital loss carryforwards, Expiration Period	2018
Tax credit carryforwards, Expiration Periods	2018
State [Member] \| Maximum [Member]
Tax Credit Carryforward [Line Items]
Capital loss carryforwards, Expiration Period	2037
Tax credit carryforwards, Expiration Periods	2032

Income Taxes, Reconciliation of Change in Unrecognized Income Tax Benefits, Excluding Interest and Penalties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 110	$ 124	$ 150	$ 178
Unrecognized tax benefits that would reduce the effective income tax rate				$ 157
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	110	124	150
Additions for tax positions related to the current year	14	16	14
Additions for tax positions related to prior years	66	2	2
Reductions for tax positions related to prior years	(4)	(24)	(34)
Reductions for tax positions related to settlements with taxing authorities	0	(1)	(1)
Reduction for tax positions related to prior years as a result of a lapse of statute of limitations	(8)	(7)	(7)
Balance at December 31	$ 178	$ 110	$ 124

Income Taxes, Income Tax Returns (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Anticipated decrease in unrecognized tax benefits over the next 12 months	$ 6
Reversal of previously accrued income tax expense, including interest and penalties	4	$ 25	$ 9
Accrued potential interest included within current and non-current income taxes payable	15	11
Accrued potential interest included within current and non-current income taxes payable after income taxes	11	7
Potential penalties	8	7
Benefit (Expense) Related Items Included in Income Taxes Expenses	5	$ (3)
Deferred taxes for the repatriation of earnings from certain subsidiaries			$ 17
Undistributed earnings of non-U.S. Companies	$ 844

Stock-Based Compensation, Stock-Based Compensation Plans (Details) - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 03, 2016	Feb. 23, 2016	Feb. 22, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of L-3 Holdings common stock available to be awarded (in shares)					4,260	3,690
Share-based Compensation Arrangement by Share-based Payment Award [Abstract]
Stock based compensation	$ 57	$ 49	$ 49
Income taxes	(12)	(18)	(18)
Total after income taxes	45	31	31
Less: Stock-based compensation recorded in discontinued operations, net of income taxes	1	1	1
Stock-based compensation recorded in continuing operations, net of income taxes	44	30	30
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Abstract]
Stock based compensation	7	10	9
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Abstract]
Stock based compensation	43	35	38
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Abstract]
Stock based compensation	$ 7	$ 4	$ 2
2008 Long Term Performance Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of additional shares authorized for issuance under the amendment (in shares)				6,800
Number of shares authorized for issuance under the amendment (in shares)				26,000
Maximum number of shares of L-3 Holdings common stock may be issued pursuant to "full value" awards under the amendment (in shares)	7,900

Stock-Based Compensation, Stock Options (Details) - Stock Options [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of stock options granted from date of grant	10 years
Vesting period	3 years
Weighted average grant date fair value of stock options (in dollars per share)	$ 28.35	$ 15.90	$ 19.76
Intrinsic value of stock options exercised	$ 44	$ 34	$ 35
Unrecognized compensation costs related to stock awards	7
Unrecognized compensation costs related to equity awards after income taxes	$ 6
Weighted average remaining period for recognition of unrecognized costs related to equity awards	1 year 3 months 18 days
Actual income tax benefit realized related to compensation deductions arising from the exercise of stock options	$ 16	$ 12	$ 13
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning Balance, Outstanding (in shares)	2,847,500
Options granted (in shares)	470,500
Options exercised (in shares)	(521,300)
Options forfeited (in shares)	(97,800)
Ending Balance, Outstanding (in shares)	2,698,900	2,847,500
Vested and expected to vest (in shares)	2,582,500
Exercisable (in shares)	1,762,400
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Beginning Balance, Outstanding (in dollars per share)	$ 99.54
Options granted (in dollars per share)	174.53
Options exercised (in dollars per share)	90.13
Options forfeited (in dollars per share)	120.59
Ending Balance, Outstanding (in dollars per share)	113.67	$ 99.54
Vested and expected to vest (in dollars per share)	110.21
Exercisable (in dollars per share)	$ 95.80
Weighted Average Remaining Contractual Term [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	5 years 8 months 12 days	6 years 1 month 6 days
Vested and expected to vest	5 years 6 months
Exercisable	4 years 6 months
Aggregate Intrinsic Value [Abstract]
Beginning Balance, Outstanding	$ 150
Ending Balance, Outstanding	227	$ 150
Vested and expected to Vest	226
Exercisable	$ 180
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected holding period	5 years 2 months 12 days	5 years	5 years
Expected volatility	19.90%	21.30%	21.40%
Expected dividend yield	2.00%	2.80%	2.40%
Risk-free interest rate	2.00%	1.10%	1.50%

Stock-Based Compensation, Restricted Stock Units (Details) - Restricted Stock [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Weighted average grant date fair value (in dollars per share)	$ 169.23	$ 116.72	$ 128.59
Length of service after grant date	1 year
Retirement eligibility, employee age	60 years
Service period, minimum	5 years
Retirement eligibility, employee age with no service requirement	65 years
Unrecognized compensation costs related to stock awards	$ 34
Unrecognized compensation costs related to equity awards after income taxes	$ 26
Weighted average remaining period for recognition of unrecognized costs related to equity awards	1 year 1 month 6 days
Fair value of restricted stock unit awards vested	$ 53	$ 57	$ 82
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning Balance, Nonvested (in shares)	977,900
Granted (in shares)	305,600
Vested (in shares)	(318,400)
Forfeited (in shares)	(62,400)
Ending Balance, Nonvested (in shares)	902,700	977,900
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning Balance, Nonvested (in dollars per share)	$ 119.55
Granted (in dollars per share)	169.23	$ 116.72	$ 128.59
Vested (in dollars per share)	114.46
Forfeited (in dollars per share)	134.56
Ending Balance, Nonvested (in dollars per share)	$ 137.12	$ 119.55
Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year

Stock-Based Compensation, Performance Units (Details) - Performance Units [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 168.80	$ 116.20	$ 129.03
Length of service after grant date	3 years	3 years	3 years
Unrecognized compensation costs related to stock awards	$ 5
Unrecognized compensation costs related to equity awards after income taxes	$ 5
Weighted average remaining period for recognition of unrecognized costs related to equity awards	1 year 8 months 12 days
Total performance units earned (in shares)	48,365
Fair market value performance units earned as of their vesting date	$ 10
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning Balance, Nonvested (in shares)	124,700
Granted (in shares)	33,900
Increase due to expected performance (in shares)	29,700
Vested (in shares)	(48,400)
Forfeited (in shares)	(7,800)
Ending Balance, Nonvested (in shares)	132,100	124,700
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning Balance, Nonvested (in dollars per share)	$ 120.83
Granted (in dollars per share)	168.80	$ 116.20	$ 129.03
Increase due to expected performance (in dollars per share)	146.89
Vested (in dollars per share)	129.03
Forfeited (in dollars per share)	121.06
Ending Balance, Nonvested (in dollars per share)	$ 135.99	$ 120.83
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout Range	200.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout Range	0.00%

Stock-Based Compensation, Employee Stock Purchase Plan (Details) - USD ($) $ / shares in Units, shares in Millions		12 Months Ended
	Jan. 31, 2018	Dec. 31, 2017	May 03, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee discount on the purchase of common stock		5.00%
2008 Long Term Performance Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance under the amendment (in shares)			26.0
2009 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of fair market value for offering period		95.00%
Offering period to purchase shares		6 months
Share purchases funded through payroll deductions, value		$ 21,250
Issued shares under the ESPP (in shares)		0.1
Average price of issued shares under the ESPP (in dollars per share)		$ 158.59
Number of shares authorized for issuance under the amendment (in shares)		3.5
2009 Employee Stock Purchase Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share purchases funded through payroll deductions, percentage		10.00%
2009 Employee Stock Purchase Plan [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issued shares under the ESPP (in shares)	0.1
Average price of issued shares under the ESPP (in dollars per share)	$ 188.72

Commitments and Contingencies, Non-Cancelable Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018	$ 106
2019	84
2020	108
2021	60
2022	57
Thereafter	236
Total minimum payments required	651
Sublease rentals under non-cancelable leases	(9)
Net minimum payments required	642
Rent expense, net of sublease income	103	$ 97	$ 102
Sublease rental income	1	$ 2	$ 2
Real Estate [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018	101
2019	81
2020	106
2021	60
2022	57
Thereafter	236
Total minimum payments required	641
Sublease rentals under non-cancelable leases	(9)
Net minimum payments required	632
Equipment [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018	5
2019	3
2020	2
2021	0
2022	0
Thereafter	0
Total minimum payments required	10
Sublease rentals under non-cancelable leases	0
Net minimum payments required	$ 10

Commitments and Contingencies, Letters of Credit and Guarantees (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Total outstanding letters of credit		$ 416	$ 402
Available borrowings under Credit Facility		$ 1,000
Number of existing real estate lease agreements		3
Real estate lease agreements, expiry date		Aug. 31, 2020
Purchase price of property on or before expiration date		$ 45
Residual guarantee amount		39
Maximum amount of supplemental rent payment		6
Aggregate residual guarantee amount		$ 39
Simulator Systems [Member]
Loss Contingencies [Line Items]
Operating lease agreements, term of contract		15 years
Simulator Systems [Member] \| Forecast [Member]
Loss Contingencies [Line Items]
Purchase of simulator systems	$ 15

Commitments and Contingencies, Litigation Matters (Details) - HVC Alkmaar [Member] € in Millions	Jul. 23, 2014 EUR (€)
Property Damages [Member]
Loss Contingencies [Line Items]
Claims for estimated damages	€ 11
Business Interruption [Member]
Loss Contingencies [Line Items]
Claims for estimated damages	€ 35

Pension and Other Postretirement Benefits, Changes in Benefit Obligations, Plan Assets and Funded Status and Aggregate Balance Sheet Impact (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets and (liabilities) recognized on the consolidated balance sheets consist of [Abstract]
Non-current liabilities	$ (1,313)	$ (1,177)
Pension Plans [Member]
Change in benefit obligation [Abstract]
Benefit obligation at the beginning of the year	3,758	3,448
Service cost	97	94	$ 112
Interest cost	142	135	149
Plan participants' contributions	2	2
Amendments	0	15
Actuarial loss (gain)	391	181
Foreign currency exchange rate changes	22	9
Curtailments and special termination benefits	2	2
Benefits paid	(186)	(128)
Benefit obligation at the end of the year	4,228	3,758	3,448
Change in plan assets [Abstract]
Fair value of plan assets at the beginning of the year	2,721	2,552
Actual return on plan assets	391	189
Employer contributions	97	97
Plan participants' contributions	2	2
Foreign currency exchange rate changes	22	9
Benefits paid	(186)	(128)
Fair value of plan assets at the end of the year	3,047	2,721	2,552
Unfunded status at the end of the year	(1,181)	(1,037)
Assets and (liabilities) recognized on the consolidated balance sheets consist of [Abstract]
Non-current assets	48	37
Current liabilities	(6)	(6)
Non-current liabilities	(1,223)	(1,068)
Total	(1,181)	(1,037)
Postretirement Benefit Plans [Member]
Change in benefit obligation [Abstract]
Benefit obligation at the beginning of the year	177	184
Service cost	2	2	3
Interest cost	5	6	7
Plan participants' contributions	5	4
Amendments	0	(3)
Actuarial loss (gain)	(13)	(3)
Foreign currency exchange rate changes	2	0
Curtailments and special termination benefits	0	0
Benefits paid	(13)	(13)
Benefit obligation at the end of the year	165	177	184
Change in plan assets [Abstract]
Fair value of plan assets at the beginning of the year	60	57
Actual return on plan assets	8	5
Employer contributions	7	7
Plan participants' contributions	5	4
Foreign currency exchange rate changes	0	0
Benefits paid	(13)	(13)
Fair value of plan assets at the end of the year	67	60	$ 57
Unfunded status at the end of the year	(98)	(117)
Assets and (liabilities) recognized on the consolidated balance sheets consist of [Abstract]
Non-current assets	0	0
Current liabilities	(8)	(8)
Non-current liabilities	(90)	(109)
Total	$ (98)	$ (117)

Pension and Other Postretirement Benefits, Net Loss and Prior Service Cost Balances in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain)	$ 1,035	$ 896
Prior service cost (credit)	10	14
Total amount recognized	1,045	910
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain)	(3)	(12)
Prior service cost (credit)	(27)	(4)
Total amount recognized	$ (30)	$ (16)

Pension and Other Postretirement Benefits, Aggregate Accumulated Benefit Obligation in Excess of Fair Value (Details) - Pension Plans [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Aggregate accumulated benefit obligation (ABO)	$ 3,831	$ 3,413
Projected benefit obligation	3,875	3,528
Accumulated benefit obligation	3,490	3,192
Fair value of plan assets	$ 2,651	$ 2,456

Pension and Other Postretirement Benefits, Weighted Average Assumptions Used to Determine Benefit Obligations (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pension Plans [Member]
Benefit obligations [Abstract]
Discount rate	3.78%	4.40%
Rate of compensation increase	3.50%	3.50%
Pension Plans [Member] \| U.S. [Member]
Benefit obligations [Abstract]
Rate of compensation increase	3.50%	3.50%
Assumptions used to determine net periodic benefit cost, weighted average discount rate	3.81%	4.45%
Pension Plans [Member] \| Canada [Member]
Benefit obligations [Abstract]
Rate of compensation increase	3.50%	3.50%
Assumptions used to determine net periodic benefit cost, weighted average discount rate	3.39%	3.79%
Postretirement Benefit Plans [Member]
Benefit obligations [Abstract]
Discount rate	3.59%	4.05%
Postretirement Benefit Plans [Member] \| U.S. [Member]
Benefit obligations [Abstract]
Assumptions used to determine net periodic benefit cost, weighted average discount rate	3.63%	4.11%
Postretirement Benefit Plans [Member] \| Canada [Member]
Benefit obligations [Abstract]
Assumptions used to determine net periodic benefit cost, weighted average discount rate	3.33%	3.64%

Pension and Other Postretirement Benefits, Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of net periodic benefit cost [Abstract]
Operating Income (Loss)	$ 268	$ 232	$ 294	$ 237	$ 283	$ 211	$ 220	$ 244	$ 1,031	$ 958	$ 812
Pension Plans [Member]
Components of net periodic benefit cost [Abstract]
Service cost									97	94	112
Interest cost									142	135	149
Expected return on plan assets									(197)	(186)	(194)
Amortization of prior service cost (credits)									1	0	1
Amortization of net loss (gains)									61	52	68
Curtailment loss and special termination benefits									6	2	3
Net periodic benefit cost									110	97	139
Postretirement Benefit Plans [Member]
Components of net periodic benefit cost [Abstract]
Service cost									2	2	3
Interest cost									5	6	7
Expected return on plan assets									(4)	(4)	(5)
Amortization of prior service cost (credits)									(1)	(2)	(2)
Amortization of net loss (gains)									(2)	(2)	0
Curtailment loss and special termination benefits									0	0	0
Net periodic benefit cost									0	0	3
Adjustment [Member]
Components of net periodic benefit cost [Abstract]
Operating Income (Loss)									11	1	27
Adjustment [Member] \| Pension Plans [Member]
Components of net periodic benefit cost [Abstract]
Expected return on plan assets									$ 15	$ 14	$ 11

Pension and Other Postretirement Benefits, Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract]
Net loss (gain)	$ 71
Prior service credit	(1)
Total amount expected to be amortized	70
Pension Plans [Member]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract]
Net loss (gain)	200	$ 179	$ (132)
Prior service (cost) credit	(4)	15	0
Amortization of net (loss) gain	(61)	(52)	(68)
Amortization of prior service (cost) credit	(1)	0	(1)
Total recognized in other comprehensive income (loss)	134	142	(201)
Total recognized in net periodic benefit cost and other comprehensive income (loss)	244	239	(62)
Net loss (gain)	74
Prior service credit	0
Total amount expected to be amortized	74
Postretirement Benefit Plans [Member]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract]
Net loss (gain)	(17)	(4)	(7)
Prior service (cost) credit	0	(2)	0
Amortization of net (loss) gain	2	2	0
Amortization of prior service (cost) credit	1	2	2
Total recognized in other comprehensive income (loss)	(14)	(2)	(5)
Total recognized in net periodic benefit cost and other comprehensive income (loss)	(14)	$ (2)	$ (2)
Net loss (gain)	(3)
Prior service credit	(1)
Total amount expected to be amortized	$ (4)

Pension and Other Postretirement Benefits, Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Effect of one percentage point increase on total service and interest cost	$ 0
Effect of one percentage point decrease on total service and interest cost	0
Effect of one percentage point increase on postretirement benefit obligations	5
Effect of one percentage point decrease on postretirement benefit obligations	$ (4)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	4.40%	4.67%	4.14%
Service cost	4.55%	4.83%	0.00%
Interest cost	3.84%	3.95%	0.00%
Expected long-term return on plan assets	7.92%	7.92%	8.14%
Rate of compensation increase	3.50%	3.50%	3.50%
Pension Plans [Member] \| U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	4.45%	4.73%	4.20%
Expected long-term return on plan assets	8.00%	8.00%	8.25%
Rate of compensation increase	3.50%	3.50%	3.50%
Health care cost trend rate, covering retirees under 65 years of age next fiscal year	6.50%
Health care cost trend rate, covering retirees over 65 years of age next fiscal year	8.00%
Pension Plans [Member] \| U.S. [Member] \| 2021 and Thereafter [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate, covering retirees under 65 years of age	5.00%
Pension Plans [Member] \| U.S. [Member] \| 2024 and Thereafter [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate, covering retirees over 65 years of age	5.00%
Pension Plans [Member] \| Canada [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	3.79%	3.93%	3.90%
Expected long-term return on plan assets	7.25%	7.25%	7.25%
Rate of compensation increase	3.50%	3.50%	3.50%
Health care cost trend rate next fiscal year	6.25%
Pension Plans [Member] \| Canada [Member] \| 2023 and Thereafter [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate	5.00%
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	4.05%	4.22%	3.70%
Service cost	4.21%	4.37%	0.00%
Interest cost	3.26%	3.26%	0.00%
Expected long-term return on plan assets	7.43%	7.42%	7.65%
Postretirement Benefit Plans [Member] \| U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	4.11%	4.28%	3.70%
Postretirement Benefit Plans [Member] \| Canada [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	3.64%	3.74%	3.70%

Pension and Other Postretirement Benefits, Weighted Average Asset Allocations by Asset Category (Details) - Pension and Postemployment Retirement Benefit Plans [Member]

Dec. 31, 2017

Dec. 31, 2016

U.S. [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

100.00%

U.S. [Member] | Total Equities [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

58.00%

65.00%

U.S. [Member] | Total Equities [Member] | Minimum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

45.00%

U.S. [Member] | Total Equities [Member] | Maximum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

75.00%

U.S. [Member] | Domestic Equity [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

47.00%

55.00%

U.S. [Member] | Domestic Equity [Member] | Minimum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

30.00%

U.S. [Member] | Domestic Equity [Member] | Maximum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

60.00%

U.S. [Member] | International Equity [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

11.00%

10.00%

U.S. [Member] | International Equity [Member] | Minimum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

10.00%

U.S. [Member] | International Equity [Member] | Maximum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

20.00%

U.S. [Member] | Total Fixed Income Securities and Cash and Cash Equivalents [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

^[1]

Weighted-average asset allocations

^[1]

U.S. [Member] | Fixed Income Securities [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

28.00%

22.00%

U.S. [Member] | Fixed Income Securities [Member] | Minimum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

20.00%

U.S. [Member] | Fixed Income Securities [Member] | Maximum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

40.00%

U.S. [Member] | Other, Primarily Cash and Cash Equivalents [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

7.00%

5.00%

U.S. [Member] | Other, Primarily Cash and Cash Equivalents [Member] | Minimum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

0.00%

U.S. [Member] | Other, Primarily Cash and Cash Equivalents [Member] | Maximum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

15.00%

U.S. [Member] | Real Estate Securities [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

7.00%

8.00%

U.S. [Member] | Real Estate Securities [Member] | Minimum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

0.00%

U.S. [Member] | Real Estate Securities [Member] | Maximum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

15.00%

Canada [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

100.00%

Canada [Member] | Total Equities [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

62.00%

77.00%

Canada [Member] | Total Equities [Member] | Minimum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

40.00%

Canada [Member] | Total Equities [Member] | Maximum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

80.00%

Canada [Member] | Domestic Equity [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

15.00%

Canada [Member] | International Equity [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

47.00%

62.00%

Canada [Member] | Total Fixed Income Securities and Cash and Cash Equivalents [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

38.00%

23.00%

Canada [Member] | Total Fixed Income Securities and Cash and Cash Equivalents [Member] | Minimum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

20.00%

Canada [Member] | Total Fixed Income Securities and Cash and Cash Equivalents [Member] | Maximum [Member]

Defined Benefit Plan Disclosure [Line Items]

Percentage of plan assets

60.00%

Canada [Member] | Fixed Income Securities [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

25.00%

13.00%

Canada [Member] | Other, Primarily Cash and Cash Equivalents [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

13.00%

10.00%

Canada [Member] | Real Estate Securities [Member]

Defined Benefit Plan Disclosure [Line Items]

Weighted-average asset allocations

0.00%

[1]	NA - Not applicable. The Company’s Master Pension Trust Investment Policy does not provide an allocation percentage range to fixed income securities and cash and cash equivalents.

Pension and Other Postretirement Benefits, Fair Value of Postretirement Benefit Plans Assets (Details) - Postretirement Benefit Plans [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity securities [Abstract]
Fair value of company's plan assets	$ 67	$ 60	$ 57
Percentage of mutual fund in total investment in fixed income - investment grade securities	77.00%	73.00%
Percentage of pooled bond funds in total investment in fixed income - investment grade securities	23.00%	27.00%
Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	$ 53	$ 49
Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	11	8
Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. Equity [Member]
Equity securities [Abstract]
Fair value of company's plan assets	38	37
U.S. Equity [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	38	37
U.S. Equity [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. Equity [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
International Equity [Member]
Equity securities [Abstract]
Fair value of company's plan assets	2	1
International Equity [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	2	1
International Equity [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
International Equity [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Fixed Income - Investment Grade [Member]
Equity securities [Abstract]
Fair value of company's plan assets	13	11
Fixed Income - Investment Grade [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	10	8
Fixed Income - Investment Grade [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	3	3
Fixed Income - Investment Grade [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Fixed Income - High Yield [Member]
Equity securities [Abstract]
Fair value of company's plan assets	3	2
Fixed Income - High Yield [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Fixed Income - High Yield [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	3	2
Fixed Income - High Yield [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Real Estate Investment Trusts [Member]
Equity securities [Abstract]
Fair value of company's plan assets	3	3
Real Estate Investment Trusts [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	3	3
Real Estate Investment Trusts [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Real Estate Investment Trusts [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Other [Member]
Equity securities [Abstract]
Fair value of company's plan assets	5	3
Other [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Other [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	5	3
Other [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Total Assets at Fair Value [Member]
Equity securities [Abstract]
Fair value of company's plan assets	64	57
Other Investments Measured at Net Asset Value [Member]
Equity securities [Abstract]
Liabilities for unsettled trades, net	$ 3	$ 3

Pension and Other Postretirement Benefits, Contributions (Details) $ in Millions	Dec. 31, 2017 USD ($)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions to plans in 2018	$ 100
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions to plans in 2018	$ 10

Pension and Other Postretirement Benefits, Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2017 USD ($)
Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2018	$ 158
2019	165
2020	175
2021	185
2022	194
Years 2023-2027	1,128
Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2018	12
2019	12
2020	13
2021	13
2022	12
Years 2023-2027	55
Subsidy Receipts, 2018	0
Subsidy Receipts, 2019	0
Subsidy Receipts, 2020	0
Subsidy Receipts, 2021	0
Subsidy Receipts, 2022	0
Subsidy Receipts, Years 2023-2027	$ 1

Pension and Other Postretirement Benefits, Employee Savings Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Continuing Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Company's matching contributions in L-3 Holdings' common stock and cash	$ 115	$ 118	$ 131
Discontinued Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Company's matching contributions in L-3 Holdings' common stock and cash	$ 8	$ 12	$ 24

Pension and Other Postretirement Benefits, Multi-Employer Benefit Plans (Details)
$ in Millions

12 Months Ended

Dec. 31, 2017

USD ($)

PensionFunds

Dec. 31, 2016

USD ($)

Dec. 31, 2015

USD ($)

Multiemployer Plans [Line Items]

Contributions by L-3 Communications

$ 27

$ 26

$ 23

Minimum percentage funded to have green zone status rating

80.00%

Percentage of total plan contributions

5.00%

Percentage of contributions from reportable segment

61.00%

Expiration date of multiple bargaining agreements

Apr. 28, 2019

Number of pension funds included in Other Pension Funds | PensionFunds

Discontinued Operations [Member]

Multiemployer Plans [Line Items]

Contributions by L-3 Communications

$ 26

$ 22

IAM National Pension Fund [Member]

Multiemployer Plans [Line Items]

Contributions by L-3 Communications

$ 27

$ 26

EIN/Pension Plan Number

51-6031295/002

Pension Protection Act Zone Status

Green

FIP/RP Status Pending/Implemented

Surcharge Imposed

Expiration Date of Collective-Bargaining Agreement, First

^[1]

Apr. 29, 2018

Expiration Date of Collective-Bargaining Agreement, Last

^[1]

Sep. 30, 2020

Other Pension Funds [Member]

Multiemployer Plans [Line Items]

Contributions by L-3 Communications

$ 0

[1]

The Company is a party to multiple bargaining agreements for multiple projects that require contributions into the IAM National Pension Fund. The most significant of these agreements, expiring April 28, 2019, covers multiple programs in the Company’s ISRS reportable segment and represents 61% of 2017 contributions.

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Interest paid	$ 165	$ 162	$ 182
Income tax payments	163	120	130
Income tax refunds	$ 16	$ 8	$ 8

Segment Information, Products and Services (Details)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2017

USD ($)

Sep. 29, 2017

USD ($)

Jun. 30, 2017

USD ($)

Mar. 31, 2017

USD ($)

Dec. 31, 2016

USD ($)

Sep. 23, 2016

USD ($)

Jun. 24, 2016

USD ($)

Mar. 25, 2016

USD ($)

Dec. 31, 2017

USD ($)

Segment

Dec. 31, 2016

USD ($)

Dec. 31, 2015

USD ($)

Segment Reporting [Abstract]

Number of reportable segments | Segment

Corporate expenses

$ 32

$ 29

Segment Reporting Information, Revenue for Reportable Segment [Abstract]

Products

6,733

6,453

6,600

Services

2,840

2,757

2,631

Revenue, Net

$ 2,574

$ 2,293

$ 2,385

$ 2,321

$ 2,643

$ 2,184

$ 2,318

$ 2,065

9,573

9,210

9,231

Segment Reporting Information, Operating Income (Loss) [Abstract]

Operating income

268

$ 232

$ 294

$ 237

283

$ 211

$ 220

$ 244

1,031

958

812

Goodwill impairment charge

(46)

(31)

Depreciation, Depletion and Amortization [Abstract]

Depreciation and amortization

225

198

203

Capital Expenditures [Abstract]

Capital Expenditures

224

210

195

Total Assets [Abstract]

Total Assets

12,729

11,865

12,729

11,865

12,069

Assets held for sale

135

Assets of discontinued operations

306

481

306

481

1,124

NSS Including Business Retained [Member] | Continuing Operations [Member]

Segment Reporting Information, Operating Income (Loss) [Abstract]

Goodwill impairment charge

^[1]

(46)

Operating Segments [Member]

Segment Reporting Information, Operating Income (Loss) [Abstract]

Operating income

1,031

958

889

Operating Segments [Member] | ISRS [Member]

Segment Reporting Information, Revenue for Reportable Segment [Abstract]

Products

2,540

2,662

2,696

Services

1,463

1,450

1,403

Segment Reporting Information, Operating Income (Loss) [Abstract]

Operating income

348

362

312

Depreciation, Depletion and Amortization [Abstract]

Depreciation and amortization

Capital Expenditures [Abstract]

Capital Expenditures

Total Assets [Abstract]

Total Assets

4,135

4,117

4,135

4,117

4,219

Operating Segments [Member] | C&NS [Member]

Segment Reporting Information, Revenue for Reportable Segment [Abstract]

Products

2,424

2,238

2,244

Services

717

678

637

Segment Reporting Information, Operating Income (Loss) [Abstract]

Operating income

362

298

288

Depreciation, Depletion and Amortization [Abstract]

Depreciation and amortization

Capital Expenditures [Abstract]

Capital Expenditures

Total Assets [Abstract]

Total Assets

3,505

3,258

3,505

3,258

3,222

Operating Segments [Member] | Electronic Systems [Member]

Segment Reporting Information, Revenue for Reportable Segment [Abstract]

Products

1,814

1,617

1,716

Services

695

653

612

Segment Reporting Information, Operating Income (Loss) [Abstract]

Operating income

321

298

289

Depreciation, Depletion and Amortization [Abstract]

Depreciation and amortization

Capital Expenditures [Abstract]

Capital Expenditures

Total Assets [Abstract]

Total Assets

3,939

3,542

3,939

3,542

3,159

Corporate [Member]

Capital Expenditures [Abstract]

Capital Expenditures

Total Assets [Abstract]

Total Assets

$ 709

$ 467

709

467

345

Elimination of Intercompany Sales [Member]

Segment Reporting Information, Revenue for Reportable Segment [Abstract]

Products

(45)

(64)

(56)

Services

$ (35)

$ (24)

$ (21)

[1]	Represents non-cash goodwill impairment charges recorded during 2015 of $46 million related to a business retained by L3 in connection with the sale of the NSS segment.

Segment Information, Geographic Location (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 1,110				$ 1,107				$ 1,110	$ 1,107
Net sales	2,574	$ 2,293	$ 2,385	$ 2,321	2,643	$ 2,184	$ 2,318	$ 2,065	9,573	9,210	$ 9,231
U.S. Government Agencies [Member]
Segment Reporting Information [Line Items]
Net sales									6,697	6,399	6,120
Commercial [Member]
Segment Reporting Information [Line Items]
Net sales									1,456	1,280	1,373
Foreign Governments [Member]
Segment Reporting Information [Line Items]
Net sales									1,420	1,531	1,738
Reportable Geographical Components [Member] \| U.S. [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	936				960				936	960
Net sales									7,344	6,947	6,734
Reportable Geographical Components [Member] \| United Kingdom [Member]
Segment Reporting Information [Line Items]
Net sales									335	331	336
Reportable Geographical Components [Member] \| Canada [Member]
Segment Reporting Information [Line Items]
Net sales									280	297	281
Reportable Geographical Components [Member] \| Australia [Member]
Segment Reporting Information [Line Items]
Net sales									268	254	321
Reportable Geographical Components [Member] \| China [Member]
Segment Reporting Information [Line Items]
Net sales									167	67	83
Reportable Geographical Components [Member] \| South Korea [Member]
Segment Reporting Information [Line Items]
Net sales									134	127	207
Reportable Geographical Components [Member] \| Japan [Member]
Segment Reporting Information [Line Items]
Net sales									125	81	95
Reportable Geographical Components [Member] \| FRANCE
Segment Reporting Information [Line Items]
Net sales									84	75	62
Reportable Geographical Components [Member] \| Other [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 174				$ 147				174	147
Net sales									836	1,031	1,112
Reportable Geographical Components [Member] \| Total International [Member]
Segment Reporting Information [Line Items]
Net sales									$ 2,229	$ 2,263	$ 2,497

Severance and Restructuring Related Costs (Details) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) Employee	Dec. 31, 2016 USD ($) Employee	Dec. 31, 2015 USD ($) Employee
Restructuring Cost and Reserve [Line Items]
Severance and restructuring costs			$ 91	$ 13	$ 14
Number of employees of restructuring costs \| Employee			1,500	700	800
Gain (loss) on sale of property	$ (12)	$ 42
Restructuring Reserve [Roll Forward]
Balance at beginning of period			$ 9
Additional provisions			101
Cash payments			(87)
Balance at end of period	$ 23		23	$ 9
ISRS [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring costs			38	5	$ 8
Curtailment loss			5
C&NS [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring costs			52	8	7
Electronic Systems [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring costs			11	4	3
Curtailment loss			1
Consolidated Entities [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring costs			$ 101	$ 17	$ 18

Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Data [Line Items]
Revenue, Net	$ 2,574	$ 2,293	$ 2,385	$ 2,321	$ 2,643	$ 2,184	$ 2,318	$ 2,065	$ 9,573	$ 9,210	$ 9,231
Operating income	268	232	294	237	283	211	220	244	1,031	958	812
Income from continuing operations	271	146	195	157	187	149	134	163	769	633	507
Net (loss) income	293	25	207	168	192	151	151	230	693	724	(225)
Net income attributable to L3	$ 289	$ 22	$ 202	$ 164	$ 188	$ 148	$ 147	$ 227	$ 677	$ 710	$ (240)
Basic EPS from continuing operations (in dollars per share)	$ 3.42	$ 1.83	$ 2.44	$ 1.97	$ 2.37	$ 1.89	$ 1.68	$ 2.06	$ 9.65	$ 7.99	$ 6.10
Basic EPS (in dollars per share)	3.70	0.28	2.59	2.11	2.43	1.91	1.90	2.92	8.68	9.17	(2.97)
Diluted EPS from continuing operations (in dollars per share)	3.34	1.79	2.39	1.93	2.32	1.85	1.66	2.02	9.46	7.86	6.01
Earnings Per Share, Diluted	$ 3.62	0.28	$ 2.54	$ 2.07	$ 2.38	$ 1.88	$ 1.88	$ 2.87	$ 8.51	$ 9.01	$ (2.93)
Goodwill impairment charges									$ 0	$ 0	$ 46
Estimated tax benefit amount	$ (79)								(79)
Earnings per share, diluted (in dollars per share)	$ 0.99
Vertex Aerospace [Member]
Quarterly Financial Data [Line Items]
Earnings Per Share, Diluted		$ 1.67
Goodwill impairment charges		$ 187							$ 187

Financial Information of L3 and Its Subsidiaries, Condensed Combining Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 662	$ 363	$ 207	$ 442
Billed receivables, net	723	700
Contracts in process	1,933	1,858
Prepaid expenses and other current assets	689	505
Assets held for sale	135	0	0
Assets of discontinued operations	306	481	1,124
Total current assets	4,448	3,907
Goodwill	6,615	6,374	6,095
Other assets	1,666	1,584
Investment in and amounts due from consolidated subsidiaries	0	0
Total assets	12,729	11,865	12,069
Current liabilities	2,136	1,959
Liabilities held for sale	17	0
Liabilities of discontinued operations	226	235
Amounts due to consolidated subsidiaries	0	0
Other long-term liabilities	1,869	1,722
Long-term debt	3,330	3,325
Total liabilities	7,578	7,241
L3 shareholders' equity	5,083	4,553
Noncontrolling interests	68	71
Total equity	5,151	4,624	4,429	5,360
Total liabilities and equity	12,729	11,865
Subsidiaries [Member]
Current assets:
Cash and cash equivalents	432	262	109	358
Billed receivables, net	266	261
Contracts in process	706	694
Prepaid expenses and other current assets	330	236
Assets held for sale	0
Assets of discontinued operations	306	481
Total current assets	2,040	1,934
Goodwill	2,099	2,110
Other assets	658	705
Investment in and amounts due from consolidated subsidiaries	5,662	5,653
Total assets	10,459	10,402
Current liabilities	811	789
Liabilities held for sale	0
Liabilities of discontinued operations	226	235
Amounts due to consolidated subsidiaries	0	0
Other long-term liabilities	1,009	1,500
Long-term debt	3,330	3,325
Total liabilities	5,376	5,849
L3 shareholders' equity	5,083	4,553
Noncontrolling interests	0	0
Total equity	5,083	4,553
Total liabilities and equity	10,459	10,402
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	16	5	0	4
Billed receivables, net	244	261
Contracts in process	912	936
Prepaid expenses and other current assets	235	145
Assets held for sale	135
Assets of discontinued operations	0	0
Total current assets	1,542	1,347
Goodwill	2,932	2,785
Other assets	687	592
Investment in and amounts due from consolidated subsidiaries	6,310	5,563
Total assets	11,471	10,287
Current liabilities	832	833
Liabilities held for sale	17
Liabilities of discontinued operations	0	0
Amounts due to consolidated subsidiaries	0	0
Other long-term liabilities	729	192
Long-term debt	0	0
Total liabilities	1,578	1,025
L3 shareholders' equity	9,893	9,262
Noncontrolling interests	0	0
Total equity	9,893	9,262
Total liabilities and equity	11,471	10,287
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	285	203	165	142
Billed receivables, net	213	178
Contracts in process	315	228
Prepaid expenses and other current assets	124	124
Assets held for sale	0
Assets of discontinued operations	0	0
Total current assets	937	733
Goodwill	1,584	1,479
Other assets	321	287
Investment in and amounts due from consolidated subsidiaries	0	0
Total assets	2,842	2,499
Current liabilities	564	444
Liabilities held for sale	0
Liabilities of discontinued operations	0	0
Amounts due to consolidated subsidiaries	391	832
Other long-term liabilities	131	30
Long-term debt	0	0
Total liabilities	1,086	1,306
L3 shareholders' equity	1,756	1,193
Noncontrolling interests	0	0
Total equity	1,756	1,193
Total liabilities and equity	2,842	2,499
Eliminations [Member]
Current assets:
Cash and cash equivalents	(71)	(107)	$ (67)	$ (62)
Billed receivables, net	0	0
Contracts in process	0	0
Prepaid expenses and other current assets	0	0
Assets held for sale	0
Assets of discontinued operations	0	0
Total current assets	(71)	(107)
Goodwill	0	0
Other assets	0	0
Investment in and amounts due from consolidated subsidiaries	(11,972)	(11,216)
Total assets	(12,043)	(11,323)
Current liabilities	(71)	(107)
Liabilities held for sale	0
Liabilities of discontinued operations	0	0
Amounts due to consolidated subsidiaries	(391)	(832)
Other long-term liabilities	0	0
Long-term debt	0	0
Total liabilities	(462)	(939)
L3 shareholders' equity	(11,649)	(10,455)
Noncontrolling interests	68	71
Total equity	(11,581)	(10,384)
Total liabilities and equity	$ (12,043)	$ (11,323)

Financial Information of L3 and Its Subsidiaries, Condensed Combining Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Revenue, Net	$ 2,574	$ 2,293	$ 2,385	$ 2,321	$ 2,643	$ 2,184	$ 2,318	$ 2,065	$ 9,573	$ 9,210	$ 9,231
Total cost of sales									(8,542)	(8,252)	(8,342)
Goodwill impairment charges									0	0	(46)
(Loss) gain related to business divestitures									0	0	(31)
Operating Income (Loss)	268	232	294	237	283	211	220	244	1,031	958	812
Interest expense									(169)	(164)	(162)
Interest and other income, net									9	17	(10)
Debt retirement charges									0	(7)	(1)
Income from continuing operations before income taxes									871	804	639
Provision for income taxes									(102)	(171)	(132)
Equity in net income (loss) of consolidated subsidiaries									0	0	0
Income from continuing operations	271	146	195	157	187	149	134	163	769	633	507
(Loss) income from discontinued operations, net of income taxes									(76)	91	(732)
Net (loss) income	293	25	207	168	192	151	151	230	693	724	(225)
Net income attributable to noncontrolling interests									(16)	(14)	(15)
Net income (loss) attributable to L-3	$ 289	$ 22	$ 202	$ 164	$ 188	$ 148	$ 147	$ 227	677	710	(240)
Comprehensive (loss) income attributable to L3									712	558	(230)
Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue, Net									3,520	3,351	3,268
Total cost of sales									(3,169)	(3,064)	(3,017)
Goodwill impairment charges											0
(Loss) gain related to business divestitures											(13)
Operating Income (Loss)									351	287	238
Interest expense									(168)	(164)	(161)
Interest and other income, net									6	9	3
Debt retirement charges										(7)	(1)
Income from continuing operations before income taxes									189	125	79
Provision for income taxes									(22)	(26)	(16)
Equity in net income (loss) of consolidated subsidiaries									586	520	429
Income from continuing operations									753	619	492
(Loss) income from discontinued operations, net of income taxes									(76)	91	(732)
Net (loss) income									677	710	(240)
Net income attributable to noncontrolling interests									0	0	0
Net income (loss) attributable to L-3									677	710	(240)
Comprehensive (loss) income attributable to L3									712	558	(230)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue, Net									4,852	4,842	4,870
Total cost of sales									(4,446)	(4,406)	(4,429)
Goodwill impairment charges											(26)
(Loss) gain related to business divestitures											(31)
Operating Income (Loss)									406	436	384
Interest expense									0	0	(1)
Interest and other income, net									(8)	(3)	(15)
Debt retirement charges										0	0
Income from continuing operations before income taxes									398	433	368
Provision for income taxes									(47)	(92)	(76)
Equity in net income (loss) of consolidated subsidiaries									144	130	73
Income from continuing operations									495	471	365
(Loss) income from discontinued operations, net of income taxes									0	0	0
Net (loss) income									495	471	365
Net income attributable to noncontrolling interests									0	0	0
Net income (loss) attributable to L-3									495	471	365
Comprehensive (loss) income attributable to L3									604	409	255
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue, Net									1,581	1,348	1,444
Total cost of sales									(1,307)	(1,113)	(1,247)
Goodwill impairment charges											(20)
(Loss) gain related to business divestitures											13
Operating Income (Loss)									274	235	190
Interest expense									(1)	0	0
Interest and other income, net									11	11	2
Debt retirement charges										0	0
Income from continuing operations before income taxes									284	246	192
Provision for income taxes									(33)	(53)	(40)
Equity in net income (loss) of consolidated subsidiaries									0	0	0
Income from continuing operations									251	193	152
(Loss) income from discontinued operations, net of income taxes									0	0	0
Net (loss) income									251	193	152
Net income attributable to noncontrolling interests									0	0	0
Net income (loss) attributable to L-3									251	193	152
Comprehensive (loss) income attributable to L3									378	116	41
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue, Net									(380)	(331)	(351)
Total cost of sales									380	331	351
Goodwill impairment charges											0
(Loss) gain related to business divestitures											0
Operating Income (Loss)									0	0	0
Interest expense									0	0	0
Interest and other income, net									0	0	0
Debt retirement charges										0	0
Income from continuing operations before income taxes									0	0	0
Provision for income taxes									0	0	0
Equity in net income (loss) of consolidated subsidiaries									(730)	(650)	(502)
Income from continuing operations									(730)	(650)	(502)
(Loss) income from discontinued operations, net of income taxes									0	0	0
Net (loss) income									(730)	(650)	(502)
Net income attributable to noncontrolling interests									(16)	(14)	(15)
Net income (loss) attributable to L-3									(746)	(664)	(517)
Comprehensive (loss) income attributable to L3									$ (982)	$ (525)	$ (296)

Financial Information of L3 and Its Subsidiaries, Condensed Combining Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net cash from operating activities from continuing operations	$ 985	$ 1,022	$ 1,035
Investing activities:
Business acquisitions, net of cash acquired	(316)	(388)	(320)
Proceeds from sale of business, net of closing date cash balances	18	561	318
Other investing activities	(155)	(183)	(188)
Net cash used in investing activities from continuing operations	(453)	(10)	(190)
Financing activities:
Proceeds from sale of senior notes	0	547	0
Redemption of senior notes	0	(856)	(297)
Common stock repurchased	(180)	(373)	(740)
Dividends paid on L3's common stock	(236)	(220)	(214)
Other financing activities	50	46	46
Net cash used in financing activities from continuing operations	(366)	(856)	(1,205)
Effect of foreign currency exchange rate changes on cash	20	(13)	(19)
Net increase in cash and cash equivalents of discontinued operations	113	13	83
Change in cash balance in assets held for sale	0	0	61
Net (decrease) increase in cash	299	156	(235)
Cash and cash equivalents, beginning of the year	363	207	442
Cash and cash equivalents, end of the year	662	363	207
Subsidiaries [Member]
Operating activities:
Net cash from operating activities from continuing operations	374	440	633
Investing activities:
Business acquisitions, net of cash acquired	(316)	(388)	(320)
Proceeds from sale of business, net of closing date cash balances	17	563	42
Other investing activities	(92)	(63)	(75)
Net cash used in investing activities from continuing operations	(391)	112	(353)
Financing activities:
Proceeds from sale of senior notes		547
Redemption of senior notes		(856)	(297)
Common stock repurchased	(180)	(373)	(740)
Dividends paid on L3's common stock	(236)	(220)	(214)
Other financing activities	490	490	639
Net cash used in financing activities from continuing operations	74	(412)	(612)
Effect of foreign currency exchange rate changes on cash	0	0	0
Net increase in cash and cash equivalents of discontinued operations	113	13	83
Change in cash balance in assets held for sale			0
Net (decrease) increase in cash	170	153	(249)
Cash and cash equivalents, beginning of the year	262	109	358
Cash and cash equivalents, end of the year	432	262	109
Guarantor Subsidiaries [Member]
Operating activities:
Net cash from operating activities from continuing operations	426	509	428
Investing activities:
Business acquisitions, net of cash acquired	0	0	0
Proceeds from sale of business, net of closing date cash balances	0	0	0
Other investing activities	(38)	(77)	(78)
Net cash used in investing activities from continuing operations	(38)	(77)	(78)
Financing activities:
Proceeds from sale of senior notes		0
Redemption of senior notes		0	0
Common stock repurchased	0	0	0
Dividends paid on L3's common stock	0	0	0
Other financing activities	(377)	(427)	(355)
Net cash used in financing activities from continuing operations	(377)	(427)	(355)
Effect of foreign currency exchange rate changes on cash	0	0	0
Net increase in cash and cash equivalents of discontinued operations	0	0	0
Change in cash balance in assets held for sale			1
Net (decrease) increase in cash	11	5	(4)
Cash and cash equivalents, beginning of the year	5	0	4
Cash and cash equivalents, end of the year	16	5	0
Non-Guarantor Subsidiaries [Member]
Operating activities:
Net cash from operating activities from continuing operations	263	259	159
Investing activities:
Business acquisitions, net of cash acquired	0	0	0
Proceeds from sale of business, net of closing date cash balances	1	(2)	276
Other investing activities	(25)	(43)	(35)
Net cash used in investing activities from continuing operations	(24)	(45)	241
Financing activities:
Proceeds from sale of senior notes		0
Redemption of senior notes		0	0
Common stock repurchased	0	0	0
Dividends paid on L3's common stock	0	0	0
Other financing activities	(177)	(163)	(418)
Net cash used in financing activities from continuing operations	(177)	(163)	(418)
Effect of foreign currency exchange rate changes on cash	20	(13)	(19)
Net increase in cash and cash equivalents of discontinued operations	0	0	0
Change in cash balance in assets held for sale			60
Net (decrease) increase in cash	82	38	23
Cash and cash equivalents, beginning of the year	203	165	142
Cash and cash equivalents, end of the year	285	203	165
Eliminations [Member]
Operating activities:
Net cash from operating activities from continuing operations	(78)	(186)	(185)
Investing activities:
Business acquisitions, net of cash acquired	0	0	0
Proceeds from sale of business, net of closing date cash balances	0	0	0
Other investing activities	0	0	0
Net cash used in investing activities from continuing operations	0	0	0
Financing activities:
Proceeds from sale of senior notes		0
Redemption of senior notes		0	0
Common stock repurchased	0	0	0
Dividends paid on L3's common stock	0	0	0
Other financing activities	114	146	180
Net cash used in financing activities from continuing operations	114	146	180
Effect of foreign currency exchange rate changes on cash	0	0	0
Net increase in cash and cash equivalents of discontinued operations	0	0	0
Change in cash balance in assets held for sale			0
Net (decrease) increase in cash	36	(40)	(5)
Cash and cash equivalents, beginning of the year	(107)	(67)	(62)
Cash and cash equivalents, end of the year	$ (71)	$ (107)	$ (67)

Financial Information of L3 and Its Subsidiaries - Additional Information (Details) - Understatement [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net income of consolidated subsidiaries and Net income of Guarantor Subsidiaries	$ 144	$ 130	$ 73
Guarantor Subsidiaries [Member] \| Investment in and Amounts due from Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revision of misstated asset amount in previously issued financial statements	1,646	1,256
Guarantor Subsidiaries [Member] \| Total Assets [Member]
Condensed Financial Statements, Captions [Line Items]
Revision of misstated asset amount in previously issued financial statements	1,646	1,256
Guarantor Subsidiaries [Member] \| Total Equity [Member]
Condensed Financial Statements, Captions [Line Items]
Revision of misstated equity amount in previously issued financial statements	$ 1,646	$ 1,256

Pension and Other Postretirement Benefits, Fair Value of Pension Plan Assets (Details) - Pension Plans [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity securities [Abstract]
Fair value of company's plan assets	$ 3,047	$ 2,721	$ 2,552
U.S. [Member]
Equity securities [Abstract]
Liabilities for unsettled trades, net	(30)	(23)
Fair value of company's plan assets	$ 2,704	$ 2,421
Percentage of mutual fund in total investment in fixed income - investment grade securities	62.00%	62.00%
Percentage of pooled bond funds in total investment in fixed income - investment grade securities	38.00%	38.00%
U.S. [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	$ 1,909	$ 1,864
U.S. [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	622	409
U.S. [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| U.S. Equity [Member]
Equity securities [Abstract]
Fair value of company's plan assets	1,297	1,331
U.S. [Member] \| U.S. Equity [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	1,297	1,331
U.S. [Member] \| U.S. Equity [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| U.S. Equity [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| International Equity [Member]
Equity securities [Abstract]
Fair value of company's plan assets	87	85
U.S. [Member] \| International Equity [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	87	85
U.S. [Member] \| International Equity [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| International Equity [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| Fixed Income - Investment Grade [Member]
Equity securities [Abstract]
Fair value of company's plan assets	534	414
U.S. [Member] \| Fixed Income - Investment Grade [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	329	255
U.S. [Member] \| Fixed Income - Investment Grade [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	205	159
U.S. [Member] \| Fixed Income - Investment Grade [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| Fixed Income - High Yield [Member]
Equity securities [Abstract]
Fair value of company's plan assets	219	136
U.S. [Member] \| Fixed Income - High Yield [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| Fixed Income - High Yield [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	219	136
U.S. [Member] \| Fixed Income - High Yield [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| Real Estate Investment Trusts [Member]
Equity securities [Abstract]
Fair value of company's plan assets	196	193
U.S. [Member] \| Real Estate Investment Trusts [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	196	193
U.S. [Member] \| Real Estate Investment Trusts [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| Real Estate Investment Trusts [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| Other [Member]
Equity securities [Abstract]
Fair value of company's plan assets	198	114
U.S. [Member] \| Other [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| Other [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	198	114
U.S. [Member] \| Other [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
U.S. [Member] \| Total Assets at Fair Value [Member]
Equity securities [Abstract]
Fair value of company's plan assets	2,531	2,273
U.S. [Member] \| Other Investments Measured at Net Asset Value [Member]
Equity securities [Abstract]
Fair value of company's plan assets	203	171
Canada [Member]
Equity securities [Abstract]
Liabilities for unsettled trades, net	0	0
Fair value of company's plan assets	$ 343	$ 300
Percentage of mutual fund investment in equity trust funds	31.00%	55.00%
Percentage of pooled bond fund investment in equity trust funds	69.00%	45.00%
Canada [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	$ 184	$ 188
Canada [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	37	27
Canada [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| U.S. Equity [Member]
Equity securities [Abstract]
Fair value of company's plan assets	71	79
Canada [Member] \| U.S. Equity [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	71	79
Canada [Member] \| U.S. Equity [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| U.S. Equity [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| International Equity [Member]
Equity securities [Abstract]
Fair value of company's plan assets	105	104
Canada [Member] \| International Equity [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	105	104
Canada [Member] \| International Equity [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| International Equity [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Fixed Income - Investment Grade [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Fixed Income - Investment Grade [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Fixed Income - Investment Grade [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Fixed Income - Investment Grade [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Fixed Income - High Yield [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Fixed Income - High Yield [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Fixed Income - High Yield [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Fixed Income - High Yield [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Real Estate Investment Trusts [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Real Estate Investment Trusts [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Real Estate Investment Trusts [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Real Estate Investment Trusts [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Other [Member]
Equity securities [Abstract]
Fair value of company's plan assets	45	32
Canada [Member] \| Other [Member] \| Level 1 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	8	5
Canada [Member] \| Other [Member] \| Level 2 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	37	27
Canada [Member] \| Other [Member] \| Level 3 [Member]
Equity securities [Abstract]
Fair value of company's plan assets	0	0
Canada [Member] \| Total Assets at Fair Value [Member]
Equity securities [Abstract]
Fair value of company's plan assets	221	215
Canada [Member] \| Other Investments Measured at Net Asset Value [Member]
Equity securities [Abstract]
Fair value of company's plan assets	$ 122	$ 85