L3 10-Q 25 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 28, 2018	Oct. 19, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	L3 TECHNOLOGIES, INC.
Entity Central Index Key	1,039,101
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		78,697,551
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 28, 2018
Entity Emerging Growth Company	false
Entity Small Business	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 28, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 507	$ 662
Billed receivables, net of allowances of $12 in 2018 and $18 in 2017	900	723
Contract assets	1,707	0
Contracts in process	0	1,933
Inventories	911	389
Prepaid expenses and other current assets	410	300
Assets held for sale	0	135
Assets of discontinued operations	0	306
Total current assets	4,435	4,448
Property, plant and equipment, net	1,156	1,110
Goodwill	6,834	6,615
Identifiable intangible assets	414	292
Other assets	345	264
Total assets	13,184	12,729
Current liabilities:
Accounts payable, trade	619	531
Accrued employment costs	482	493
Accrued expenses	268	217
Contract liabilities	578	0
Advance payments and billings in excess of costs incurred	0	509
Income taxes payable	14	19
Other current liabilities	299	367
Liabilities held for sale	0	17
Liabilities of discontinued operations	0	226
Total current liabilities	2,260	2,379
Pension and postretirement benefits	1,230	1,313
Deferred income taxes	221	158
Other liabilities	442	398
Long-term debt	3,320	3,330
Total liabilities	7,473	7,578
Commitments and contingencies (see Note 19)
Shareholders’ equity:
Common stock: $.01 par value; 300,000,000 shares authorized, 78,597,571 shares outstanding at September 28, 2018 and 77,876,687 shares outstanding at December 31, 2017	6,808	6,519
Treasury stock (at cost), 84,999,711 shares at September 28, 2018 and 83,362,412 shares at December 31, 2017	(7,726)	(7,404)
Retained earnings	7,263	6,659
Accumulated other comprehensive loss	(703)	(691)
Total shareholders’ equity	5,642	5,083
Noncontrolling interests	69	68
Total equity	5,711	5,151
Total liabilities and equity	$ 13,184	$ 12,729

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 28, 2018	Dec. 31, 2017
Current assets:
Allowances for billed receivables	$ 12	$ 18
Shareholders’ equity:
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)	78,597,571	77,876,687
Treasury stock at cost (in shares)	84,999,711	83,362,412

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	Jul. 10, 2018	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Net sales:
Total sales		$ 2,519	$ 2,293	$ 7,473	$ 6,999
Operating costs and expenses:
General and administrative expenses		(396)	(380)	(1,176)	(1,097)
Total operating costs and expenses		(2,238)	(2,061)	(6,668)	(6,236)
Loss on sale of the Crestview Aerospace and TCS businesses		(4)	0	44	0
Merger, acquisition and divestiture related expenses		(5)	0	(5)	0
Operating income		272	232	844	763
Interest expense		(40)	(42)	(125)	(126)
Interest and other income, net		15	2	29	8
Debt retirement charge		(21)	0	(69)	0
Income from continuing operations before income taxes		226	192	679	645
Provision for income taxes		(18)	(46)	(90)	(147)
Income from continuing operations		208	146	589	498
Loss from discontinued operations, net of income taxes		0	(121)	206	(98)
Net income		208	25	795	400
Net income from continuing operations attributable to noncontrolling interests		(6)	(3)	(15)	(12)
Net income attributable to L3		$ 202	$ 22	$ 780	$ 388
Basic earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)		$ 2.57	$ 1.83	$ 7.32	$ 6.23
Discontinued operations (in dollars per share)		0	(1.55)	2.63	(1.26)
Basic earnings per share (in dollars per share)		2.57	0.28	9.95	4.97
Diluted earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)		2.54	1.79	7.21	6.10
Discontinued operations (in dollars per share)		0	(1.51)	2.59	(1.23)
Diluted earnings per share (in dollars per share)		2.54	0.28	9.80	4.87
Cash dividends declared per common share (in dollars per share)	$ 0.80	$ 0.8	$ 0.75	$ 2.40	$ 2.25
Weighted average common shares outstanding:
Basic (in shares)		78.5	78.2	78.4	78
Diluted (in shares)		79.4	79.8	79.6	79.6
Product [Member]
Net sales:
Total sales		$ 1,736	$ 1,584	$ 5,168	$ 4,868
Operating costs and expenses:
Cost of Goods and services sold		(1,324)	(1,189)	(3,864)	(3,630)
Service [Member]
Net sales:
Total sales		783	709	2,305	2,131
Operating costs and expenses:
Cost of Goods and services sold		$ (518)	$ (492)	$ (1,628)	$ (1,509)

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Statement of Comprehensive Income [Abstract]
Net income		$ 208	$ 25	$ 795	$ 400
Other comprehensive income (loss):
Foreign currency translation adjustments		(3)	49	(42)	120
Unrealized gains (losses) on hedging instruments (1)	[1]	2	6	(9)	6
Pension and postretirement benefit plans:
Amortization of net loss and prior service cost previously recognized (2)	[2]	12	8	39	27
Total other comprehensive income (loss)		11	63	(12)	153
Comprehensive income		219	88	783	553
Comprehensive income attributable to noncontrolling interests		(6)	(3)	(15)	(12)
Comprehensive income attributable to L3		$ 213	$ 85	$ 768	$ 541
[1]	Net of income taxes of $1 million and $2 million for the quarterly periods ended September 28, 2018 and September 29, 2017, respectively, and net of income tax benefit of $2 million and net of income taxes of $2 million for the year-to-date periods ended September 28, 2018 and September 29, 2017, respectively.
[2]	Net of income taxes of $4 million and $5 million for the quarterly periods ended September 28, 2018 and September 29, 2017, respectively, and net of income taxes of $12 million and $16 million for the year-to-date periods ended September 28, 2018 and September 29, 2017, respectively.

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Statement of Comprehensive Income [Abstract]
Income tax benefit on unrealized losses on hedging instruments	$ 1	$ 2	$ (2)	$ 2
Income tax (expense) on amortization of net loss and prior service cost previously recognized	$ 4	$ 5	$ 12	$ 16

UNAUDITED CONDENSED CONSOLIDA_4

UNAUDITED CONDENSED 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, 2016	$ 4,624	$ 1	$ 6,284	$ (7,224)	$ 6,218	$ (726)	$ 71
Beginning Balance (in shares) at Dec. 31, 2016		77.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	400				388		12
Other comprehensive income (loss)	153					153
Distributions to noncontrolling interests	(13)						(13)
Cash dividends declared	(177)				(177)
Shares issued:
Employee savings plans	96		96
Employee savings plans (in shares)		0.6
Exercise of stock options	36		36
Exercise of stock options (in shares)		0.4
Employee stock purchase plan	16		16
Employee stock purchase plan (in shares)		0.2
Vesting of restricted stock and performance units	0
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	43		43
Treasury stock purchased	(91)			(91)
Treasury stock purchased (in shares)		(0.5)
Ending Balance at Sep. 29, 2017	5,069	$ 1	6,457	(7,315)	6,429	(573)	70
Ending Balance (in shares) at Sep. 29, 2017		78.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment of ASC 606 on January 1, 2018, net of taxes	13				13
Beginning Balance at Dec. 31, 2017	5,151	$ 1	6,518	(7,404)	6,659	(691)	68
Beginning Balance (in shares) at Dec. 31, 2017		77.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	795				780		15
Other comprehensive income (loss)	(12)					(12)
Distributions to noncontrolling interests	(14)						(14)
Cash dividends declared	(189)				(189)
Shares issued:
Employee savings plans	98		98
Employee savings plans (in shares)		0.5
Exercise of stock options	142		142
Exercise of stock options (in shares)		1.4
Employee stock purchase plan	17		17
Employee stock purchase plan (in shares)		0.2
Vesting of restricted stock and performance units	0
Vesting of restricted stock and performance units (in shares)		0.3
Repurchases of common stock to satisfy tax withholding obligations	(24)		(24)
Repurchases of common stock to satisfy tax withholding obligations (in shares)		(0.1)
Stock-based compensation expense	47		47
Treasury stock purchased	(322)			(322)
Treasury stock purchased (in shares)		(1.6)
Other	9		9
Ending Balance at Sep. 28, 2018	$ 5,711	$ 1	$ 6,807	$ (7,726)	$ 7,263	$ (703)	$ 69
Ending Balance (in shares) at Sep. 28, 2018		78.6

UNAUDITED CONDENSED CONSOLIDA_5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	Jul. 10, 2018	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 0.80	$ 0.8	$ 0.75	$ 2.40	$ 2.25

UNAUDITED CONDENSED CONSOLIDA_6

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Operating activities:
Net income	$ 795	$ 400
Less: (income) loss from discontinued operations, net of tax	(206)	98
Income from continuing operations	589	498
Depreciation of property, plant and equipment	132	125
Amortization of intangibles and other assets	38	36
Deferred income tax provision	26	30
Stock-based employee compensation expense	47	43
Contributions to employee savings plans in common stock	94	90
Amortization of pension and postretirement benefit plans net loss and prior service cost	51	43
Loss (gain) on sale of property, plant and equipment	1	(42)
Gain on sale of the Crestview Aerospace and TCS businesses	(44)	0
Debt retirement charges	69	0
Other non-cash items	5	9
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures, and discontinued operations:
Billed receivables	(166)	3
Contract assets	(361)	0
Contracts in process	0	(183)
Inventories	28	(46)
Prepaid expenses and other current assets	(127)	(29)
Accounts payable, trade	57	47
Accrued employment costs	(10)	12
Accrued expenses	71	54
Contract liabilities	7	0
Advance payments and billing in excess of costs incurred	0	(18)
Income taxes	(25)	2
All other operating activities	(140)	(93)
Net cash from operating activities from continuing operations	342	581
Investing activities:
Business acquisitions, net of cash acquired	(368)	(291)
Proceeds from the sale of businesses, net of closing date cash balances	535	18
Capital expenditures	(167)	(151)
Dispositions of property, plant and equipment	2	67
Other investing activities	(28)	(7)
Net cash used in investing activities from continuing operations	(26)	(364)
Financing activities:
Proceeds from sale of senior notes	1,798	0
Repurchases and redemptions of senior notes	(1,865)	0
Borrowings under revolving credit facility	501	1,265
Repayments of borrowings under revolving credit facility	(501)	(1,265)
Common stock repurchased	(322)	(91)
Dividends paid	(191)	(178)
Proceeds from exercises of stock options	142	36
Proceeds from employee stock purchase plan	25	24
Repurchases of common stock to satisfy tax withholding obligations	(24)	(18)
Debt issue costs	(16)	0
Other financing activities	(16)	(12)
Net cash used in financing activities from continuing operations	(469)	(239)
Effect of foreign currency exchange rate changes on cash and cash equivalents	(9)	16
Net cash from (used in) discontinued operations:
Operating activities	9	84
Investing activities	(2)	(2)
Net cash from discontinued operations	7	82
Net (decrease) increase cash and cash equivalents	(155)	76
Cash and cash equivalents, beginning of the period	662	363
Cash and cash equivalents, end of the period	$ 507	$ 439

Description of Business

Description of Business	9 Months Ended
	Sep. 28, 2018
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. Effective in the third quarter of 2018, the Company realigned its reportable segments. Prior to the realignment the Company had the following four reportable segments: (1) Electronic Systems, (2) Aerospace Systems, (3) Communication Systems and (4) Sensor Systems. The realignment: (i) combined the Aerospace Systems segment with the Sensor Systems segment to form a new reportable segment named the ISR Systems (ISRS) segment, (ii) moved the Naval Power Systems businesses from the Electronic Systems segment to the Communication Systems segment and changed the name of the Communication Systems segment to the Communications & Networked Systems (C&NS) segment and (iii) moved the Maritime Sensor Systems businesses from the former Sensor Systems segment to the C&NS segment. Accordingly, the Company's current structure consists of the following three segments: (1) ISRS, (2) C&NS and (3) Electronic Systems. ISRS provides products and services for the global ISR and Command, Control and Communications (C 3 ) markets, specializing in ISR mission solutions from seabed to space, 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 and Intelligence & Mission Systems. 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 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. Financial information with respect to the Company’s segments is included in Note 23 to the unaudited condensed consolidated financial statements. On June 29, 2018, the Company completed the sale of its Vertex Aerospace businesses for a sale price of $540 million subject to customary closing net working capital adjustments. In connection with the sale, the Company recognized: (1) a pre-tax gain from continuing operations of $44 million ( $22 million after income taxes) related to the Crestview Aerospace and TCS businesses (the "Crestview & TCS Businesses") and (2) a pre-tax gain from discontinued operations of $237 million ( $180 million after income taxes) related to the Vertex Aerospace business. 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 for the year ended December 31, 2017. The assets and liabilities and results of operations of the Vertex Aerospace business are reported as discontinued operations for all periods presented. See Note 5 for additional information. All references made to financial data in this Quarterly Report on Form 10-Q are to the Company’s continuing operations, unless specifically noted.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 28, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These unaudited condensed consolidated financial statements for the quarterly and year-to-date periods ended September 28, 2018 should be read in conjunction with the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . Principles of Consolidation and Reporting 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 and variable interest entities (VIEs) if the Company is the primary beneficiary. The Company also holds interests in certain VIEs for which it was determined the Company is not the primary beneficiary. 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 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 certain current 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. Certain reclassifications have been made to conform prior-year amounts to the current-year presentation. The unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (SEC). Accordingly, they do not include all of the disclosures required by U.S. GAAP for a complete set of annual audited financial statements. The December 31, 2017 condensed consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by U.S. GAAP. In the opinion of management, all adjustments (consisting of normal and recurring adjustments) considered necessary for a fair statement of the results for the interim periods presented have been included. The results of operations for the interim periods are not necessarily indicative of results for the full year. It is generally the Company’s established practice to close its books for the quarters ending March, June and September on the Friday preceding the end of the calendar quarter. The interim unaudited condensed consolidated financial statements included herein have been prepared and are labeled based on that convention. The Company closes its books for annual periods on December 31 regardless of what day it falls on. Accounting Estimates The preparation of financial statements in conformity with 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 sales, profit and loss recognition related to performance obligations satisfied over time, fair values of assets acquired and liabilities assumed in business combinations and investments, market values for inventories reported at lower of cost or market, pension and postretirement 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. Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers, as amended (commonly referred to as ASC 606) using the modified retrospective transition method. The cumulative effect of applying the standard was an increase of $13 million to shareholders' equity as of January 1, 2018. The Company’s statement of operations for the quarterly and year-to-date periods ended September 28, 2018 and the Company’s balance sheet as of September 28, 2018 are presented under ASC 606, while the Company’s statement of operations for the quarterly and year-to-date periods ended September 29, 2017 and the Company’s balance sheet as of December 31, 2017 are presented under ASC 605, Revenue Recognition . See Note 3 for disclosure of the impact of the adoption of ASC 606 on the Company’s statement of operations for the quarterly and year-to-date periods ended September 28, 2018 and balance sheet as of September 28, 2018 and the effect of changes made to the Company’s consolidated balance sheet as of January 1, 2018. A substantial majority of the Company’s consolidated net sales are generated from long-term contracts with customers that require it to design, develop, manufacture, modify, upgrade, test and integrate complex aerospace and electronic equipment and to provide engineering and technical services according to the customers’ specifications. These contracts are primarily with agencies of, and prime system contractors to, the U.S. Government and foreign governments and are generally priced on a fixed-price, cost-plus or time-and-material type basis. Substantially all of the Company's cost-plus and time-and-material type contracts are with the U.S. Government, primarily the DoD. Certain of the Company’s contracts with the U.S. Government are multi-year contracts incrementally funded by the customer. The transaction price on these incrementally funded contracts includes contract value amounts not yet funded by the U.S. Government when the Company has a firm order for the goods or services and it is probable that the customer will fund such amounts. In assessing probability, the Company considers, among other factors, the period of time before contract funding is expected, communication from the customer that indicates funding will be obtained and the Company's history of receiving funding under the current contract or previous similar contracts. The Company also generates sales to a lesser extent from contracts with commercial and government customers for standard product and service offerings, which are priced on a firm fixed basis. See Note 23 for additional information regarding the composition of the Company’s net sales. The Company records sales for a contract when it has the approval and commitment of all parties, the contract identifies the rights of the parties and payment terms, the contract has commercial substance and collectability of the consideration is probable. To determine the proper revenue recognition method, the Company first evaluates each of its contractual arrangements to identify its performance obligations. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer. The majority of the Company’s contracts have a single performance obligation because the promise to transfer the individual good or service is not separately identifiable from other promises within the contract and is, therefore, not distinct. These contractual arrangements either require the use of a highly specialized manufacturing process to provide goods according to customer specifications or represent a bundle of contracted goods and services that are integrated and together represent a combined output, which may include the delivery of multiple units. Some of the Company's contracts have multiple performance obligations, primarily (i) related to the provision of multiple goods or services that have alternative use to the Company or that are not substantially the same or (ii) due to the contract covering multiple phases of the product lifecycle (development and engineering, production, maintenance and support). For contracts with more than one performance obligation, the Company allocates the total transaction price in an amount based on the estimated relative standalone selling prices underlying each performance obligation. In cases where a contract requires a customized good or service, the primary method used to estimate standalone selling price is the expected cost plus a margin approach. In cases where the Company sells a standard product or service offering, the standalone selling price is based on an observable standalone selling price. The majority of the Company's sales are from performance obligations satisfied over time and are primarily with agencies of, and prime system contractors to, the U.S. Government and foreign governments. Sales are recognized over time when control is continuously transferred to the customer during the contract. For U.S. Government contracts, the continuous transfer of control to the customer is supported by contract clauses that provide for (i) progress or performance-based payments or (ii) the unilateral right of the customer to terminate the contract for its convenience, in which case the Company has the right to receive payment for costs incurred plus a reasonable profit for products and services that do not have alternative use to the Company. Foreign government and certain commercial contracts contain similar termination for convenience clauses, or the Company has a legally enforceable right to receive payment for costs incurred and a reasonable profit for products or services that do not have alternative use to the Company. Sales on fixed price and cost-plus type contracts that include performance obligations satisfied over time are generally recorded at amounts equal to the ratio of actual cumulative costs incurred divided by total estimated costs at completion, multiplied by (i) the transaction price, less (ii) the cumulative sales recognized in prior periods (cost-to-cost method). Accounting for the sales and profits on performance obligations for which progress is measured using the cost-to-cost method involves the preparation of estimates of: (1) transaction price and (2) total costs at completion, which is equal to the sum of the actual incurred costs to date on the contract and the estimated costs to complete the contract's statement of work. Incurred costs include labor, material, overhead and, for the Company's U.S. Government contractor businesses, general and administrative (G&A) expenses. Incurred costs represent work performed, which corresponds with and thereby represents the transfer of control to the customer. The estimated profit or loss at completion on a contract is equal to the difference between the transaction price and the total estimated cost at completion. In the case of a contract related to complex aerospace or electronic equipment for which the total estimated costs exceed the total transaction price, a loss arises, and a provision for the entire loss is recorded in the period that the loss becomes evident. The unrecoverable costs on a loss contract that are expected to be incurred in the future periods are presented on the balance sheet as a component of other current liabilities entitled "Estimated cost in excess of estimated contract value to complete contracts in process in a loss position." See Note 10 for additional information. The Company’s contracts give rise to variable consideration, including award and incentive fees, as well as amounts incrementally funded by the U.S. Government, or other provisions that can either increase or decrease the transaction price. Award fees provide for a fee based on actual performance relative to contractually specified performance criteria. Incentive fees provide for a fee based on the relationship between total allowable costs and target costs. Variable consideration may require the Company to exercise significant judgment to determine the total transaction price of the contract. The Company includes variable consideration in the transaction price when there is a basis to reasonably estimate the variable amount it will be entitled to receive and it is probable that a significant reversal in revenue recognized will not be required when the uncertainty is resolved. These estimates are based on historical experience, current and forecasted performance, and the Company’s judgment at the time of the evaluation. Contract modifications routinely occur to account for changes in contract specifications or requirements. In most cases, contract modifications are for goods or services that are not distinct and, therefore, are accounted for as part of the existing contract. Transaction price estimates include additional consideration for submitted contract modifications or claims when the Company believes it has an enforceable right to the modification or claim, the amount can be reliably estimated and its realization is reasonably assured. Amounts representing modifications accounted for as part of the existing contract are included in the transaction price and recognized as an adjustment to sales on a cumulative catch-up basis. The Company’s fixed-price type contracts with the U.S. Government typically allow for progress payments or performance-based payments. Progress payments are billed to the customer as contract costs are incurred at an amount generally equal to 80% of incurred costs. Performance based payments are billed to the customer upon the achievement of predetermined performance milestones at amounts not to exceed 90% of contract price. On contracts with progress or performance-based payments, the customer often retains a small portion of the contract price until satisfactory completion of the contractual statement of work. Since a small portion of the contract price is retained, the Company generally recognizes sales in excess of billings, which are presented as contract assets on the balance sheet. The portion of the contract price retained by the customer is a normal business practice to ensure satisfactory contract completion and, therefore, is not considered a significant financing component. Contract assets also arise from cost-plus type contracts, time-and-material type contracts and fixed-price services 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. For certain fixed-price contracts with foreign governments and commercial customers, the Company receives advance payments. Advanced payments are not considered a significant financing component because they are a negotiated contract term to ensure the customer meets its financial obligation, particularly when there are significant upfront working capital requirements. The Company records a liability for advance payments received in excess of sales recognized, which is presented as a contract liability on the balance sheet. Revisions or adjustments to estimates of the transaction price, estimated costs at completion and estimated profit or loss of a performance obligation 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 or loss estimates 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 contract assets and inventories, and in some cases result in liabilities to complete contracts in a loss position. The aggregate impact of net changes in contract estimates is presented in the table below. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Operating income $ 56 $ 55 $ 172 $ 139 Diluted earnings per share $ 0.54 $ 0.44 $ 1.64 $ 1.12 Net sales recognized from the Company's performance obligations partially satisfied in prior periods were $83 million and $213 million for the quarterly and year-to-date periods ended September 28, 2018 , respectively, and relate to revisions in contract estimates. Sales from performance obligations satisfied at a point in time are typically for standard goods and are recognized when the customer obtains control, which is generally upon delivery and acceptance. The Company also records sales for performance obligations relating to standard services (i.e., maintenance and extended warranties covering standard goods sold by the Company) over time by using output measures of time elapsed to measure progress toward satisfying the performance obligation. Sales on time-and-material type contracts are generally recognized each period based on the amount billable to the customer, which is based on direct labor hours expended multiplied by the contractual fixed rate per hour, plus the actual costs of materials and other direct non-labor costs. The following table presents a summary of the Company’s net sales by revenue recognition method as a percentage of total net sales for the year-to-date period ended September 28, 2018 . % of Total Net Sales Cost to cost method 75 % Point in time 18 % Output method 4 % Billing method 3 % Total 100 % Remaining Performance Obligations On September 28, 2018 , the Company had $11.0 billion of remaining performance obligations, which represents the transaction price of firm orders less inception to date sales recognized. Remaining performance obligations exclude unexercised contract options and potential orders under basic ordering agreements or master-type contracts (i.e., indefinite-delivery, indefinite-quantity). The Company expects to recognize sales relating to existing performance obligations of approximately $2.5 billion during the remainder of 2018, $5.4 billion in 2019, $1.7 billion in 2020 and $1.4 billion in the periods thereafter. General and Administrative Expenses The Company accounts for the portion of their G&A, independent research and development (IRAD) and bids and proposal (B&P) costs that are allowable and reimbursable under U.S. Government procurement regulations on their U.S. Government contracts as contract costs which 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. G&A expenses for the Company's commercial businesses are expensed as incurred. The total research and development expenses incurred were $82 million and $243 million for the quarterly and year-to-date period s ended September 28, 2018 , respectively. The total research and development expenses incurred were $75 million and $203 million for the quarterly and year-to-date period s ended September 29, 2017 , respectively. The Company capitalizes the incremental costs of obtaining a contract with foreign governments and foreign and domestic commercial customers (third-party sales commissions) if the Company expects to recover the costs under the contract. The Company expenses the costs to obtain a contract as incurred when the expected amortization period is one year or less. The Company classifies the portion of capitalized costs of obtaining a contract to be amortized over the next 12 months within prepaid expense and other current assets and classifies the remaining amount within other assets in its consolidated balance sheets. Investments in and Loans to Nonconsolidated Affiliates The Company’s investments in nonconsolidated affiliates are primarily accounted for using the equity method of accounting and are carried at cost, plus or minus the Company’s share of net earnings or losses of the investment, subject to certain other adjustments. The cost of equity method investments includes transaction costs of the acquisition. As required by U.S. GAAP, to the extent that there is a basis difference between the cost and the underlying equity in the net assets of an equity investment, the Company allocates such differences between tangible and intangible assets. The Company’s share of net earnings or losses of the investment, inclusive of amortization expense for any basis difference associated with the investment, are presented in interest and other income, net, on the Company’s consolidated statements of operations. Dividends received from the investee reduce the carrying amount of the investment. Due to the timing of receiving financial information from its nonconsolidated affiliates, the Company may record its share of net earnings or losses of such affiliates on a three -month lag basis, with the exception of the amortization expense of any basis difference related to tangible and intangible assets which are recorded currently.

New Accounting Standards Implem

New Accounting Standards Implemented	9 Months Ended
	Sep. 28, 2018
Accounting Changes and Error Corrections [Abstract]
New Accounting Standards Implemented	New Accounting Standards Implemented Effective January 1, 2018, the Company adopted Financial Accounting Standards Board (FASB) 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, 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 decreased operating income and increased interest and other income, net, each by $4 million and $9 million for the quarterly and year-to-date periods ended September 28, 2018 , respectively, and increased operating income and decreased interest and other income, net, each by $3 million and $6 million for the quarterly and year-to-date periods ended September 29, 2017 , respectively. The adoption of this standard did not impact pre-tax income for the quarterly and year-to-date periods ended September 28, 2018 and September 29, 2017 . In January 2017, the FASB issued ASU 2017-01, Clarifying the Definition of a Business , which provides 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 Company adopted this amendment as of January 1, 2018. The adoption of ASU 2017-01 did not have a material impact on the Company's financial statements for the year-to-date period ended September 28, 2018 . In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , as amended (commonly referred to as ASC 606), which replaces numerous requirements in U.S. GAAP, including industry-specific requirements, and provides companies with a single revenue recognition model for recognizing revenue from contracts with customers and significantly expanded the disclosure requirements for revenue arrangements. The new standard, as amended, was effective for the Company for interim and annual reporting periods beginning on January 1, 2018. As discussed in Note 2 , the Company adopted ASC 606 using the modified retrospective transition method. Results for reporting periods beginning after December 31, 2017 are presented under ASC 606, while prior period comparative information has not been restated and continues to be reported in accordance with ASC 605, Revenue Recognition, the accounting standard in effect for periods ending prior to January 1, 2018. With the adoption of ASC 606, the Company recognizes sales over time by using the cost-to-cost method on most of its (i) contracts that were covered by the contract accounting standards under ASC 605 and (ii) fixed-price type contracts that require it to perform services that are not related to the production of tangible assets. Accordingly, the adoption of ASC 606 primarily impacted certain (i) contracts previously covered by contract accounting standards that recognized revenue using the units-of-delivery method and (ii) fixed-price type contracts for services that are not related to the production of tangible assets that recognized revenue on a straight-line basis over the contractual service period. Based on contracts in process at December 31, 2017, the Company recorded, upon adoption of ASC 606, a net increase to retained earnings of $13 million , which includes the acceleration of net sales of approximately $380 million and the related cost of sales. The adjustment to retained earnings primarily relates to contracts previously accounted for under the units-of-delivery method, which is recognized under ASC 606 earlier in the performance period as costs are incurred, as opposed to when the units are delivered under ASC 605. In accordance with the modified retrospective transition provisions of ASC 606, the Company will not recognize any of the accelerated net sales and related cost of sales at January 1, 2018 in the Company’s statements of operations for any historical or future period. The Company made certain presentation changes to its consolidated balance sheet on January 1, 2018 to comply with ASC 606. The components of contracts in process as reported under ASC 605, which included unbilled contract receivables and inventoried contract costs, have been reclassified as contract assets and inventories, respectively, after certain adjustments described below under ASC 606. The adoption of ASC 606 resulted in an increase in unbilled contract receivables (referred to as contract assets under ASC 606) primarily from converting contracts previously applying the units-of-delivery method to the cost-to-cost method with a corresponding reduction in inventoried contract costs. The remainder of inventoried contract costs, primarily related to work in process not controlled by the Company's customers, were reclassified to inventories. Additionally, under ASC 606, the Company capitalizes costs to fulfill a contract (i.e., non-recurring costs for contract-related activities that do not transfer a good or service to the customer) and costs to obtain a contract (i.e., commissions paid to third-party agents or representatives) to prepaid expense and other current assets or other assets (non-current). The Company amortizes costs to obtain a contract and costs to fulfill a contract in a pattern similar to the recognition of sales on the contracts that the capitalized costs relate to. The Company previously accounted for costs to fulfill a contract either as inventoried contract costs or expensed them as incurred. Costs to obtain a contract were generally expensed as incurred. Advance payments and billings in excess of costs and deferred revenue, previously classified in other current liabilities, have been combined and are presented as contract liabilities. The table below presents the cumulative effect of the changes made to the consolidated January 1, 2018 balance sheet due to the adoption of ASC 606. BALANCE SHEET December 31, 2017 As Reported Under ASC 605 Adjustments Due to ASC 606 January 1, 2018 As Adjusted Under ASC 606 (in millions) Assets Current assets: Contract assets $ — $ 1,349 $ 1,349 Contracts in process 1,933 (1,933 ) — Inventories 389 537 926 Prepaid expenses and other current assets 300 17 317 Assets held for sale 135 3 138 Assets of discontinued operations 306 (21 ) 285 Total current assets 4,448 (48 ) 4,400 Other assets 264 49 313 Total assets $ 12,729 $ 1 $ 12,730 Liabilities Current liabilities: Accrued expenses $ 217 $ (13 ) $ 204 Contract liabilities — 565 565 Advance payments and billing in excess of costs incurred 509 (509 ) — Other current liabilities 367 (49 ) 318 Liabilities held for sale 17 (1 ) 16 Liabilities of discontinued operations 226 (23 ) 203 Total current liabilities 2,379 (30 ) 2,349 Deferred income taxes 158 4 162 Other liabilities 398 14 412 Total liabilities 7,578 (12 ) 7,566 Shareholders' Equity Retained earnings 6,659 13 6,672 Total equity $ 5,151 $ 13 $ 5,164 The tables below present the impact of the adoption of ASC 606 on the Company's statement of operations. Third Quarter Ended September 28, 2018 STATEMENT OF OPERATIONS Under ASC 605 Effect of ASC 606 As Reported Under ASC 606 (in millions) Net Sales: Products $ 1,723 $ 13 $ 1,736 Services 772 11 783 Total 2,495 24 2,519 Operating costs and expenses: Cost of sales — Products $ (1,271 ) $ (53 ) $ (1,324 ) Cost of sales — Services (540 ) 22 (518 ) General and administrative expenses (421 ) 25 (396 ) Loss on sale of the Crestview & TCS Businesses (4 ) — (4 ) Merger, acquisition and divestiture related expenses (5 ) — (5 ) Operating income 254 18 272 Income from continuing operations before income taxes 208 18 226 Provision for income taxes (14 ) (4 ) (18 ) Income from continuing operations 194 14 208 Income from discontinued operations, net of income taxes 2 (2 ) — Net income 196 12 208 Net income attributable to L3 $ 190 $ 12 $ 202 Basic earnings per share attributable to common shareholders: Continuing operations $ 2.39 $ 0.18 $ 2.57 Discontinued operations 0.03 (0.03 ) — Basic earnings per share $ 2.42 $ 0.15 $ 2.57 Diluted earnings per share attributable to common shareholders: Continuing operations $ 2.37 $ 0.17 $ 2.54 Discontinued operations 0.02 (0.02 ) — Diluted earnings per share $ 2.39 $ 0.15 $ 2.54 Year-to-Date Ended September 28, 2018 STATEMENT OF OPERATIONS Under ASC 605 Effect of ASC 606 As Reported Under ASC 606 (in millions) Net Sales: Products $ 5,038 $ 130 $ 5,168 Services 2,290 15 2,305 Total 7,328 145 7,473 Operating costs and expenses: Cost of sales — Products $ (3,732 ) $ (132 ) $ (3,864 ) Cost of sales — Services (1,629 ) 1 (1,628 ) General and administrative expenses (1,198 ) 22 (1,176 ) Gain on sale of the Crestview & TCS Businesses 43 1 44 Merger, acquisition and divestiture related expenses (5 ) — (5 ) Operating income 807 37 844 Income from continuing operations before income taxes 642 37 679 Provision for income taxes (81 ) (9 ) (90 ) Income from continuing operations 561 28 589 Income from discontinued operations, net of income taxes 208 (2 ) 206 Net income 769 26 795 Net income attributable to L3 $ 754 $ 26 $ 780 Basic earnings per share attributable to common shareholders: Continuing operations $ 6.96 $ 0.36 $ 7.32 Discontinued operations 2.66 (0.03 ) 2.63 Basic earnings per share $ 9.62 $ 0.33 $ 9.95 Diluted earnings per share attributable to common shareholders: Continuing operations $ 6.86 $ 0.35 $ 7.21 Discontinued operations 2.61 (0.02 ) 2.59 Diluted earnings per share $ 9.47 $ 0.33 $ 9.80 The following table quantifies the impact of adopting ASC 606 on segment net sales and segment operating income for the quarterly and year-to-date periods ended September 28, 2018 . Effect of ASC 606 Third Quarter Ended September 28, 2018 Year-to-Date Ended September 28, 2018 Sales Operating Income Sales Operating Income (in millions) ISRS $ 25 $ 10 $ 47 $ 12 C&NS (18 ) 2 43 12 Electronic Systems 17 6 55 12 Segment totals $ 24 $ 18 $ 145 $ 36 The table below presents the impact of the adoption of ASC 606 on the Company's balance sheet. September 28, 2018 BALANCE SHEET Under Effect of As Reported Under ASC 606 (in millions) Assets Current assets: Contract assets $ — $ 1,707 $ 1,707 Contracts in process 2,237 (2,237 ) — Inventories 406 505 911 Prepaid expenses and other current assets 371 39 410 Total current assets 4,446 (11 ) 4,435 Other assets 298 47 345 Total assets $ 13,148 $ 36 $ 13,184 Liabilities Current liabilities: Accrued expenses $ 288 $ (20 ) $ 268 Contract liabilities — 578 578 Advance payments and billings in excess of costs incurred 536 (536 ) — Other current liabilities 351 (52 ) 299 Total current liabilities 2,290 (30 ) 2,260 Deferred income taxes 209 12 221 Other liabilities 427 15 442 Total liabilities 7,476 (3 ) 7,473 Shareholders' Equity Retained earnings 7,224 39 7,263 Total equity $ 5,672 $ 39 $ 5,711

Accounting Standards Issued and

Accounting Standards Issued and Not Yet Implemented	9 Months Ended
	Sep. 28, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Accounting Standards Issued and Not Yet Implemented	Accounting Standards Issued and Not Yet Implemented In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . The amendments in this update allow a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act (U.S. Tax Reform). The new standard is effective for the Company beginning on January 1, 2019, with early adoption permitted. The Company will adopt ASU 2018-02 effective January 1, 2019. The Company does not expect the adoption of this standard will have a material effect on its financial position, results of operations or cash flows. In August 2017, the FASB issued ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities . The amendments in this update intend to better align the Company'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 the Company 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 the Company 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 the Company 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 February 2016, the FASB issued ASU 2016-02, Leas es, 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 Company will measure leases commencing after the adoption date based on the present value of the lease payments due over the lease term (as defined in ASU 2016-02). The Company will measure and recognize its existing leases on the date of adoption based on the present value of the remaining minimum lease payments, as defined in existing guidance on accounting for leases. 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. The standard currently allows two transition methods whereby the Company may elect either to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements, with certain practical expedients available, or to initially apply the new leases standard at January 1, 2019 and recognize a cumulative-effect adjustment to the opening balance of retained earnings. The Company expects to adopt the standard as of January 1, 2019, by recognizing a cumulative-effect adjustment to the opening balance of retained earnings at January 1, 2019, in the Company’s Quarterly Report on Form 10-Q for the first quarter of 2019. Progress implementing the new standard to date includes: (1) selecting a lease accounting system, (2) electing to apply the transition practical expedients that allows the Company to rely on historical assessments of whether its contracts contain a lease and to use the same lease classifications applied under existing accounting guidance and (3) accumulating the data required to measure existing leases and prepare required disclosures. While the Company will complete its determination of the impact of adopting this standard on its consolidated financial statements in the first quarter of 2019, the Company does not expect ASU 2016-02 will have a material impact on its results of operations or cash flows. See Note 18 to the audited consolidated financial statements for the year ended December 31, 2017, included in the Company’s Annual Report on Form 10-K for additional information about the Company’s leases, including the future minimum lease payments of the Company's operating leases at December 31, 2017. In addition, the Company is in the process of redrafting its accounting policies and internal controls over financial reporting relating to lease accounting, and drafting the expanded disclosures. Other accounting standard updates effective for interim and annual periods beginning after December 31, 2018 , are not expected to have a material impact on the Company’s financial position, results of operations or cash flows.

Acquisitions, Divestitures and

Acquisitions, Divestitures and Discontinued Operations	9 Months Ended
	Sep. 28, 2018
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. 2018 Business Acquisitions ASV Global, L.L.C. (ASV Global). On September 20, 2018, the Company acquired ASV Global, L.L.C., renamed L3 ASV, for a purchase price of $94 million , which was financed with cash on hand. ASV Global is a leading unmanned surface vessel (USV) and autonomous vessel control systems company. The goodwill recognized for this business was $63 million , of which $20 million is expected to be deductible for income tax purposes and was assigned to the C&NS segment. The Company also recognized a preliminary estimate for technology intangible assets of $30 million , which is expected to be amortized over 15 years. 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 first quarter of 2019, 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. C.K. Industrial Engineers Limited. (C.K. Industrial Engineers). On September 18, 2018, the Company acquired C.K. Industrial Engineers Limited, for a purchase price of £18 million (approximately $24 million ), excluding adjustments for £3 million (approximately $4 million ) of cash acquired, which was financed with cash on hand. C.K. Industrial Engineers is a U.K.-based provider of specialized tooling and equipment used primarily in robotic solutions for automotive manufacturing. The goodwill recognized for this business was $11 million , which was assigned to the Electronic Systems 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 first quarter of 2019, 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. Azimuth Security and Linchpin Labs . (Azimuth Security and Linchpin Labs). On August 31, 2018, the Company acquired Azimuth Security and Linchpin Labs, renamed L3 Trenchant, for a combined purchase price of AUD $249 million (approximately $185 million ), net of cash acquired of AUD $21 million (approximately $15 million ), which was financed with cash on hand. The purchase price is subject to an upward adjustment for contingent consideration of up to AUD $43 million (approximately $31 million ), payable in a fixed number of shares of L3 common stock not to exceed 161,087 shares, based on L3 Trenchant's post-acquisition sales for each of the 12-month periods ending June 30, 2019, 2020 and 2021. Azimuth Security and Linchpin Labs are two information security businesses that significantly strengthen the Company's existing C 6 ISR (Command, Control, Communications, Computers, Cyber-Defense and Combat Systems, and Intelligence, Surveillance and Reconnaissance) capabilities and create synergies to drive future growth in cyber and international markets. The Company recorded a $6 million increase to equity for the preliminary acquisition date fair value of the contingent consideration . The goodwill recognized for this business was $108 million , of which $19 million is expected to be deductible for income tax purposes and was assigned to the ISRS segment. The Company also recognized a preliminary estimate for intangible assets of $98 million , primarily relating to technology and customer relationships. The technology and customer relationship intangibles are expected to be amortized over 5 years and 20 years, respectively. 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 2019, 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. Applied Defense Solutions, Inc. (Applied Defense Solutions). On June 29, 2018, the Company acquired Applied Defense Solutions, Inc., renamed L3 ADS, Inc., for a purchase price of $53 million , excluding adjustments for approximately $1 million of cash acquired, which was financed with cash on hand. Applied Defense Solutions is a leading aerospace engineering, software development and space situational awareness company. The goodwill recognized for this business was $41 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 fourth 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. Latitude Engineering, LLC (Latitude Engineering). On June 28, 2018, the Company acquired Latitude Engineering, LLC, renamed L3 Latitude Engineering, Inc., for a purchase price of $15 million , which was financed with cash on hand. The purchase price is subject to additional contingent consideration not to exceed $20 million , $15 million of which is based on Latitude Engineering’s post-acquisition financial performance for the four year period ending December 31, 2021, and the remaining $5 million is based on certain post-acquisition milestone achievements through December 31, 2020. Latitude Engineering is engaged in the design, manufacturing, integration, servicing, operation and support of hybrid quadrotor unmanned aerial systems. The Company recorded a $5 million liability as of the acquisition date for the fair value of the contingent consideration. The goodwill recognized for this business was $14 million , of which $9 million is expected to be deductible for income tax purposes and was assigned to the Electronic Systems segment. 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 fourth 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. 2017 Business Acquisitions The final purchase price and final purchase price allocations for the 2017 acquisitions of Kigre, Inc. (Kigre), Escola De Aviacao Aerocondor, S.A. (G-Air), Doss Aviation, Inc. (Doss Aviation) and Adaptive Methods, Inc. (Adaptive Methods) have been finalized as of the third quarter of 2018. The final purchase price allocations resulted in a $7 million increase to goodwill. See Note 3 to the audited consolidated financial statements for the year ended December 31, 2017 , included in the Company’s Annual Report on Form 10-K for additional information about the Company’s 2017 business acquisitions. 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 year-to-date period ended September 28, 2018 and the year ended December 31, 2017 , assuming that the business acquisitions completed during 2018 and 2017 had occurred on January 1, 2017 and January 1, 2016 , 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 2018 and 2017 acquisitions had occurred on January 1, 2017 and January 1, 2016 , respectively. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Pro forma net sales $ 2,536 $ 2,338 $ 7,553 $ 7,134 Pro forma income from continuing operations attributable to L3 $ 204 $ 144 $ 577 $ 486 Pro forma net income attributable to L3 $ 204 $ 23 $ 783 $ 388 Pro forma diluted earnings per share from continuing operations $ 2.57 $ 1.80 $ 7.25 $ 6.10 Pro forma diluted earnings per share $ 2.57 $ 0.29 $ 9.84 $ 4.87 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. Investments in Nonconsolidated Affiliates Peak Nano Optics, LLC (Peak Nano). On February 6, 2018, the Company acquired a 25% interest in Peak Nano Optics, LLC, for a purchase price of $20 million . Peak Nano is a nanotechnology company, which allows for the design and manufacturing of polymer lenses for military, sporting and commercial optics applications using its nanolayer gradient refractive index technology. The purchase price included a contingent payment of $30 million based upon Peak Nano meeting certain technical milestones on or before August 5, 2018. The Company recorded $6 million for the fair value of the contingent consideration liability on the investment date. During the quarter ended September 28, 2018, the Company reduced the fair value of the contingent consideration liability to zero as the technical milestones were not met by the deadline. Notwithstanding that Peak Nano missed the contractual deadline to meet certain technical milestones, based on continued monitoring and interactions with Peak Nano, the Company anticipates Peak Nano will achieve the technical milestones by the end of 2018. The Company determined Peak Nano is a VIE as it did not have sufficient equity at risk to finance its activities. The Company, however, is not the primary beneficiary because it does not have the power to direct the activities that are most significant to the economic performance of Peak Nano. Accordingly, Peak Nano is accounted for under the equity method of accounting. As of the acquisition date, the carrying amount of the investment was greater than the Company's equity in the underlying assets of Peak Nano due primarily to the difference in the carrying amount of the indefinite-lived amortizable intangible assets including goodwill and in-process research and development (IPR&D). The basis difference attributable to goodwill and IPR&D is $11 million and $13 million , respectively. Business Divestitures 2018 Divestitures As discussed in Note 1 , on June 29, 2018, the Company completed the sale of its Crestview & TCS Businesses . The assets and liabilities of the Crestview & TCS Businesses are classified as held for sale in the Company’s audited consolidated balance sheet as of December 31, 2017. The Crestview & TCS Businesses , which were within the Company’s ISRS segment, primarily provided 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 table below presents Crestview & TCS Businesses ’ results of operations and is included in continuing operations. Year-to-Date Ended September 28, 2018 (in millions) Net Sales $ 64 Gain on sale of businesses $ 44 Income from continuing operations before income taxes $ 47 Crestview & TCS Businesses . The major classes of assets and liabilities included as held for sale related to the Crestview & TCS Businesses are presented in the table below. December 31, (in millions) 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 Discontinued Operations Vertex Aerospace. As discussed in Note 1 , on June 29, 2018, the Company completed the sale of its Vertex Aerospace business. The table below presents the statements of operations data for Vertex Aerospace. 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 Vertex Aerospace’s net assets to the sum of: (1) L3 consolidated total net assets and (2) L3 consolidated total debt. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions) Net sales $ — $ 357 $ 597 $ 1,060 Operating costs and expenses (1) — (524 ) (561 ) (1,191 ) Operating (loss) income from discontinued operations — (167 ) 36 (131 ) Interest expense allocated to discontinued operations — (1 ) (1 ) (1 ) Gain on sale of businesses — — 237 — (Loss) income from discontinued operations before income taxes — (168 ) 272 (132 ) Income tax benefit (expense) — 47 (66 ) 34 (Loss) income from discontinued operations, net of income taxes $ — $ (121 ) $ 206 $ (98 ) __________________ (1) The Company recognized $3 million and $1 million of trailing expenses related to the sale of National Security Solutions for the year-to-date period s ended September 28, 2018 and September 29, 2017 , respectively. The major classes of assets and liabilities that were included in discontinued operations related to Vertex Aerospace are presented in the table below. These balances were classified as current at December 31, 2017 as the sale was expected to be completed within one year and the proceeds are not expected to be used to pay down long-term debt. December 31, (in millions) Assets Current assets $ 284 Property, plant and equipment, net 13 Other intangible assets 7 Other assets 2 Total assets of discontinued operations $ 306 Liabilities Accounts payable, trade $ 63 Other current liabilities 131 Current liabilities 194 Long-term liabilities 32 Total liabilities of discontinued operations $ 226 2017 Divestitures During the year-to-date period ended September 29, 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-to-Date Ended September 29, 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. Net sales and income before income taxes for Aviation Jet Services, Coleman and the Display Product Line, 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-to-Date Ended September 29, 2017 (in millions) Net sales $ 10 Income before income taxes $ 2

Contract Assets and Contract Li

Contract Assets and Contract Liabilities	9 Months Ended
	Sep. 28, 2018
Revenue from Contract with Customer [Abstract]
Contract Assets and Contract Liabilities	Contract Assets and Contract Liabilities Contract assets represent accumulated incurred costs and earned profits on contracts with customers that have been recorded as sales but have not been billed to customers and are classified as current. Contract liabilities consist of advance payments, billings in excess of costs incurred and deferred revenue which represent amounts received in excess of sales recognized on contracts. The Company classifies advance payments and billings in excess of costs incurred as current, and deferred revenue as current or non-current based on the expected timing of sales recognition. Contract assets and contract liabilities are determined on a contract by contract basis at the end of each reporting period. The non-current portion of contract liabilities is included in other liabilities in the Company's consolidated balance sheets (see Note 10 ). The table below presents the components of net contract assets. September 28, January 1, (in millions) Contract assets $ 1,707 $ 1,349 Contract liabilities — current (578 ) (565 ) Contract liabilities — non-current (31 ) (28 ) Net contract assets $ 1,098 $ 756 Contract assets increased from January 1, 2018 to September 28, 2018 by $358 million primarily due to sales exceeding billings due to contractual billing terms on U.S. Government contracts across all business areas, with the largest increases from ISR Systems, Link Training & Simulation, Space & Power Systems and Aircraft Systems. Contract liabilities increased by $16 million primarily due to advances received by ISR Systems for aircraft procurements related to U.S. and foreign government contracts and performance obligations assumed in connection with the acquisition of Trenchant, partially offset by decreases due to the liquidation of advances received by Link Training & Simulation and Advanced Communications resulting from performance on customer contracts. The Company did not recognize any impairment losses on contract assets during the quarterly and year-to-date period s ended September 28, 2018 . For the year-to-date period ended September 28, 2018 , the Company recognized sales of $403 million related to its contract liabilities at January 1, 2018. The components of contract assets are presented in the table below. September 28, January 1, (in millions) Unbilled contract receivables, gross $ 2,827 $ 2,232 Unliquidated progress payments and advances (1,120 ) (883 ) Total contract assets $ 1,707 $ 1,349

Contracts in Process

Contracts in Process	9 Months Ended
	Sep. 28, 2018
Contractors [Abstract]
Contracts in Process	Contracts in Process The components of contracts in process are presented in the table below. December 31, (in millions) Unbilled contract receivables, gross $ 1,874 Unliquidated progress payments (761 ) Unbilled contract receivables, net 1,113 Inventoried contract costs, gross 891 Unliquidated progress payments (71 ) Inventoried contract costs, net 820 Total contracts in process $ 1,933 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 operating costs and expenses by the Company’s U.S. Government contractor businesses for the quarterly and year-to-date periods ended September 29, 2017 . Third Quarter Ended Year-to-Date Ended September 29, 2017 September 29, 2017 (in millions) Amounts included in inventoried contract costs at beginning of the period $ 174 $ 173 Contract costs incurred: IRAD and B&P 88 242 Other G&A 211 610 Total 299 852 Amounts charged to operating costs and expenses (294 ) (846 ) Amounts included in inventoried contract costs at end of the period $ 179 $ 179

Inventories

Inventories	9 Months Ended
	Sep. 28, 2018
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. The Company's inventories at December 31, 2017 were comprised primarily of amounts related to standard products. In addition, the Company classified inventories related to contracts for complex aerospace and electronic equipment and engineering and technical services according to the customers' specifications as inventoried contract costs, which was a component of contracts in process on the consolidated balance sheet at December 31, 2017. See Note 7 for additional information. In accordance with ASC 606, all work in process that customers do not currently control are classified within inventories on the Company's consolidated balance sheet at September 28, 2018 , without regard to whether the goods promised to the customer are standard or customized. September 28, December 31, (in millions) Raw materials, components and sub-assemblies $ 319 $ 184 Work in process 404 98 Finished goods 188 107 Total $ 911 $ 389 Inventories at September 28, 2018 included G&A costs of $53 million . G&A costs incurred and recorded in inventories totaled $887 million during the year-to-date period ended September 28, 2018 , and G&A costs charged to expense from inventories totaled $891 million during the year-to-date period ended September 28, 2018 . See Note 7 for information on G&A costs included in contracts in process for the quarterly and year-to-date periods ended September 29, 2017 .

Goodwill and Identifiable Intan

Goodwill and Identifiable Intangible Assets	9 Months Ended
	Sep. 28, 2018
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). 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) Goodwill $ 2,504 $ 1,977 $ 2,238 $ 6,719 Accumulated impairment losses (46 ) (15 ) (43 ) (104 ) December 31, 2017 2,458 1,962 2,195 6,615 Business acquisitions (1) 150 65 30 245 Foreign currency translation adjustments (9 ) (4 ) (13 ) (26 ) September 28, 2018 2,599 2,023 2,212 6,834 Goodwill 2,645 2,038 2,255 6,938 Accumulated impairment losses (46 ) (15 ) (43 ) (104 ) $ 2,599 $ 2,023 $ 2,212 $ 6,834 __________________ (1) The increase for the ISRS segment was due to the acquisitions of the Azimuth Security, Linchpin Labs and Applied Defense Solutions businesses and the purchase price allocation adjustments for the Kigre business acquisition. The increase for the C&NS segment was due to the acquisition of the ASV Global business and purchase price allocation adjustments for the Adaptive Methods business acquisition. The increase for the Electronic Systems segment was due to the acquisitions of the Latitude Engineering and C.K. Industrial Engineers businesses and the purchase price allocation adjustments for the G-Air and Doss Aviation business acquisitions. 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. September 28, 2018 December 31, 2017 Weighted 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 16 $ 444 $ 280 $ 164 $ 393 $ 257 $ 136 Technology 9 262 124 138 189 114 75 Other 10 61 15 46 29 14 15 Total subject to amortization 767 419 348 611 385 226 IPR&D indefinite 66 — 66 66 — 66 Total $ 833 $ 419 $ 414 $ 677 $ 385 $ 292 The table below presents amortization expense recorded by the Company for its identifiable intangible assets. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, 2018 September 29, 2017 (in millions) Amortization expense $ 10 $ 10 32 30 Based on gross carrying amounts at September 28, 2018 , 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 $ 49 $ 59 $ 52 $ 45 $ 38

Other Current Liabilities and O

Other Current Liabilities and Other Liabilities	9 Months Ended
	Sep. 28, 2018
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. September 28, December 31, (in millions) Other Current Liabilities: Accrued product warranty costs $ 69 $ 69 Estimated costs in excess of estimated contract value to complete contracts in process in a loss position 46 63 Accrued interest 39 43 Estimated contingent purchase price payable for acquired businesses (see Note 16) 5 11 Deferred revenues — 38 Other 140 143 Total other current liabilities $ 299 $ 367 The table below presents the components of other liabilities. September 28, December 31, (in millions) Other Liabilities: Non-current income taxes payable (see Note 12) $ 180 $ 164 Deferred compensation 53 49 Notes payable and capital lease obligations 38 16 Contract liabilities (see Note 6) 31 — Accrued workers' compensation 24 23 Accrued product warranty costs 22 30 Estimated contingent purchase price payable for acquired businesses (see Note 16) 11 20 Deferred revenues — 19 Other 83 77 Total other liabilities $ 442 $ 398 The table below presents the changes in the Company’s accrued product warranty costs. Year-to-Date Ended September 28, September 29, (in millions) Accrued product warranty costs: Balance at January 1 $ 99 $ 109 Acquisitions during the period — 3 Accruals for product warranties issued during the period 34 34 Changes to accruals for product warranties existing before January 1 (1 ) — Settlements made during the period (41 ) (52 ) Foreign currency translation adjustments — 1 Balance at end of period $ 91 $ 95

Debt

Debt	9 Months Ended
	Sep. 28, 2018
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. September 28, December 31, (in millions) Borrowings under Revolving Credit Facility (1) $ — $ — 5.20% Senior Notes due 2019 — 1,000 4.75% Senior Notes due 2020 — 800 4.95% Senior Notes due 2021 650 650 3.85% Senior Notes due 2023 800 — 3.95% Senior Notes due 2024 350 350 3.85% Senior Notes due 2026 550 550 4.40% Senior Notes due 2028 1,000 — Principal amount of long-term debt (2) 3,350 3,350 Unamortized discounts (7 ) (7 ) Deferred debt issue costs (23 ) (13 ) Carrying amount of long-term debt $ 3,320 $ 3,330 __________________ (1) During the year-to-date period ended September 28, 2018 , L3’s aggregate borrowings and repayments under the Credit Facility were $501 million . At September 28, 2018 , L3 had the full availability of its $1 billion Credit Facility. (2) With respect to the Company’s outstanding senior notes, including the senior notes issued on June 6, 2018, upon the occurrence of both a “change in control” (as defined in the indentures governing the senior notes) along with a “change of control triggering event” (generally described as the applicable series of senior notes ceasing to be rated investment grade, 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. Issuance of Senior Notes On June 6, 2018, L3 issued two series of senior notes, which are unsecured senior obligations of L3. The terms of each series of senior notes are presented in the table below. Note Date of Issuance Amount Issued Discount (1) Net Proceeds (2) Effective Interest Rate Redemption at Treasury Rate (3)(4) (dollars in millions) 3.85% Senior Notes due June 15, 2023 (the 2023 Notes) June 6, 2018 $ 800 $ 2 $ 792 3.89 % 20 bps 4.40% Senior Notes due June 15, 2028 (the 2028 Notes) June 6, 2018 $ 1,000 $ 1 $ 990 4.41 % 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 net cash proceeds of $1,782 million (after deduction of the discount, underwriting expenses and commissions and other related expenses) plus cash on hand were used to fund the concurrent cash tender offers (the Tender Offers) for any and all of $1 billion aggregate principal amount of 5.20% Senior Notes due October 15, 2019 (the 2019 Notes) and $800 million aggregate principal amount of 4.75% Senior Notes due July 15, 2020 (the 2020 Notes) and any related redemption of notes not tendered in the Tender Offers. (3) The 2023 Notes may be redeemed at any time prior to May 15, 2023 (one month prior to maturity), and the 2028 Notes may be redeemed at any time prior to March 15, 2028 (three months prior to maturity), at the option of L3, in whole or in part, at a redemption price equal to the greater of: (i) 100% of the principal amount, or (ii) 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 2023 Notes and the 2028 Notes are redeemed at any time on or after May 15, 2023 and March 15, 2028, respectively, the redemption price would be equal to 100% of the principal amount. (4) Upon the occurrence of a change in control (as defined in the indentures governing the senior notes) along with a “change of control triggering event” (generally described as the applicable series of senior notes ceasing to be rated investment grade, 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 and Redemptions of Senior Notes The table below summarizes the Tender Offers with respect to the 2019 Notes and the 2020 Notes. Note Settlement Type Date Settled Aggregate Principal Principal Tendered Tender Premium Cash Tendered (1) Interest Total Cash Payments Debt Charge (2) (dollars in millions) 5.20% Senior Notes due 2019 Tender Offer June 6, 2018 $ 1,000 $ 683 103.282 % $ 705 $ 5 $ 710 $ 24 4.75% Senior Notes due 2020 Tender Offer June 6, 2018 $ 800 $ 535 104.092 % $ 557 $ 10 $ 567 $ 24 __________________ (1) Excludes $1 million of tender offer fees. (2) The debt retirement charge includes $1 million of tender offer fees and $3 million which represents the non-cash retirement of associated unamortized debt issue costs and discounts. On June 6, 2018, the Company initiated the redemption of the 2019 Notes and the 2020 Notes that remained outstanding subsequent to the expiration of the Tender Offers. On July 6, 2018, the Company completed the redemption of the 2019 Notes and the 2020 Notes. The terms of the 2019 Notes and the 2020 Notes redemption are presented in the table below. Note Settlement Type Date Settled Principal Redemption Premium Cash Payments Interest Total Cash Payments Debt Charge (1) (dollars in millions) 5.20% Senior Notes due 2019 Redemption July 6, 2018 $ 317 103.048 % $ 327 $ 4 $ 331 $ 10 4.75% Senior Notes due 2020 Redemption July 6, 2018 $ 265 103.818 % $ 275 $ 6 $ 281 $ 11 __________________ (1) The debt retirement charge includes $1 million which represents the non-cash retirement of associated unamortized debt issue costs and discounts. 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, jointly and severally, by L3’s material 100% owned domestic subsidiaries that guarantee any of its other indebtedness. The guarantees of the Credit Facility and the senior notes rank pari passu with each other.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 28, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes 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 September 28, 2018 , the statutes of limitations for the Company’s U.S. Federal income tax returns for the years ended December 31, 2012, 2013, 2015 and 2016 were open. The U.S. Internal Revenue Service (IRS) is auditing the Company’s U.S. Federal income tax returns for the years ended 2012 and 2013. The Company expects the audits to conclude within the next 12 months. The Company cannot predict the outcome of the audits at this time. During the quarterly period ended September 28, 2018 , the statutes of limitations for several of the Company's tax returns, including its 2014 U.S. Federal income tax return as well as certain foreign tax returns expired. As a result, the Company reduced its income tax provision by $14 million for the reversal of previously accrued amounts. The U.S. Government enacted U.S. Tax Reform on December 22, 2017, which made significant changes to the U.S. tax system. Significant changes under U.S. Tax Reform included, 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). As a result, the Company recorded an estimated tax benefit (Preliminary Net Tax Benefit) of $79 million from U.S. Tax Reform in its consolidated financial statements for the year ended December 31, 2017. In accordance with the Securities and Exchange Commission Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), the Company increased the Preliminary Net Tax Benefit by $3 million during the quarterly and year-to-date periods ended September 28, 2018 . The adjusted Preliminary Net Tax Benefit of $82 million includes a $100 million estimated tax benefit related to the remeasurement of deferred taxes partially offset by an estimated tax provision of $18 million related to the Toll Charge. SAB 118 allows for a measurement period of up to one year after the enactment date of U.S. Tax Reform to finalize the recording of the related tax impacts. As such, the Preliminary Net Tax Benefit ultimately recorded may differ in the future due principally to changes to the interpretations of U.S. Tax Reform and legislative action to clarify the interpretation of U.S. Tax Reform. Additionally, the Company is still evaluating the Global Intangible Low-Taxed Income (GILTI) provisions enacted under U.S. Tax Reform, and the associated election to record its effects as a period cost or as a component of deferred taxes. The effective income tax rate for the quarterly period ended September 28, 2018 decreased to 8.0% , compared to 24.0% for the quarterly period ended September 29, 2017 , due to the reversal of previously accrued amounts related to various U.S. Federal, foreign and state tax matters, tax benefits from U.S. Tax Reform and stock-based compensation expense. The effective income tax rate for the year-to-date period ended September 28, 2018 decreased to 13.3% , compared to 22.8% for the same period last year, due to tax benefits of U.S. Tax Reform and stock-based compensation expense, partially offset by the related income tax impact of the sale of the Crestview & TCS Businesses. At September 28, 2018 , the Company anticipates that unrecognized tax benefits will decrease by approximately $32 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. Current and non-current income taxes payable include accrued potential interest of $16 million ( $12 million after income taxes) at September 28, 2018 and $15 million ( $11 million after income taxes) at December 31, 2017 , and potential penalties of $9 million at September 28, 2018 and $8 million at December 31, 2017 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive (Loss) Income (AOCI)	9 Months Ended
	Sep. 28, 2018
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 gains (losses) on hedging instruments Unrecognized (losses) gains and prior service cost, net Total accumulated other comprehensive loss (in millions) Balance at December 31, 2017 $ (54 ) $ 9 $ (646 ) $ (691 ) Other comprehensive loss before reclassifications, net of tax (42 ) (11 ) — (53 ) Amounts reclassified from AOCI, net of tax — 2 39 41 Net current period other comprehensive (loss) income (42 ) (9 ) 39 (12 ) Balance at September 28, 2018 $ (96 ) $ — $ (607 ) $ (703 ) Balance at December 31, 2016 $ (178 ) $ 6 $ (554 ) $ (726 ) Other comprehensive income before reclassifications, net of tax 120 8 — 128 Amounts reclassified from AOCI, net of tax — (2 ) 27 25 Net current period other comprehensive income 120 6 27 153 Balance at September 29, 2017 $ (58 ) $ 12 $ (527 ) $ (573 ) 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 Unaudited Condensed Consolidated Statements of Operations Third Quarter Ended Year-to-Date Ended Details About AOCI Components September 28, September 29, September 28, September 29, (in millions) (Loss) gain on hedging instruments $ (3 ) $ 2 $ (2 ) $ 3 Cost of sales-products (3 ) 2 (2 ) 3 Income from continuing operations before income taxes — (1 ) — (1 ) Provision for income taxes $ (3 ) $ 1 $ (2 ) $ 2 Income from continuing operations Amortization of defined benefit pension and postretirement items: Net loss (b) $ (16 ) $ (13 ) $ (51 ) $ (43 ) Income from continuing operations before income taxes 4 5 12 16 Provision for income taxes $ (12 ) $ (8 ) $ (39 ) $ (27 ) Income from continuing operations Total reclassification for the period $ (15 ) $ (7 ) $ (41 ) $ (25 ) Income from continuing operations __________________ (a) Amounts in parenthesis indicate charges to the unaudited condensed 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 20 for additional information).

Equity

Equity	9 Months Ended
	Sep. 28, 2018
Equity [Abstract]
Equity	Equity On May 8, 2017, L3’s Board of Directors approved a share repurchase program that authorizes L3 to repurchase up to an additional $1.5 billion of its common stock. The 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 1,637,299 shares of its common stock at an average price of $196.64 per share for an aggregate amount of $322 million from January 1, 2018 through September 28, 2018 . All share repurchases of L3’s common stock have been recorded as treasury shares. The Company did not repurchase any shares of common stock from September 29, 2018 through October 19, 2018 . In connection with the planned merger with Harris Corporation (see Note 25 ), the Company suspended future share repurchases. On July 10, 2018 , L3’s Board of Directors declared a quarterly cash dividend of $ 0.80 per share, paid on September 17, 2018 to shareholders of record at the close of business on August 17, 2018 . During the year-to-date period ended September 28, 2018 , the Company paid $191 million of cash dividends, including a $2 million net reduction of previously accrued dividends for employee-held stock awards. On October 22, 2018 , L3’s Board of Directors declared a quarterly cash dividend of $0.80 per share, payable on December 17, 2018 to shareholders of record at the close of business on November 16, 2018 .

L3's Earnings Per Common Share

L3's Earnings Per Common Share	9 Months Ended
	Sep. 28, 2018
Earnings Per Share [Abstract]
L3's Earnings Per Common Share	L3’s Earnings Per Share A reconciliation of basic and diluted Earnings Per Share (EPS) is presented in the table below. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Reconciliation of net income: Net income $ 208 $ 25 $ 795 $ 400 Net income from continuing operations attributable to noncontrolling interests (6 ) (3 ) (15 ) (12 ) Net income attributable to L3’s common shareholders $ 202 $ 22 $ 780 $ 388 Earnings (loss) attributable to L3’s common shareholders: Continuing operations $ 202 $ 143 $ 574 $ 486 Discontinued operations, net of income tax — (121 ) 206 (98 ) Net income attributable to L3’s common shareholders $ 202 $ 22 $ 780 $ 388 Earnings per share attributable to L3’s common shareholders: Basic: Weighted average common shares outstanding 78.5 78.2 78.4 78.0 Basic earnings (loss) per share: Continuing operations $ 2.57 $ 1.83 $ 7.32 $ 6.23 Discontinued operations, net of income tax — (1.55 ) 2.63 (1.26 ) Net income $ 2.57 $ 0.28 $ 9.95 $ 4.97 Diluted: Common and potential common shares: Weighted average common shares outstanding 78.5 78.2 78.4 78.0 Effect of dilutive securities 0.9 1.6 1.2 1.6 Common and potential common shares 79.4 79.8 79.6 79.6 Diluted earnings (loss) per share: Continuing operations $ 2.54 $ 1.79 $ 7.21 $ 6.10 Discontinued operations, net of income tax — (1.51 ) 2.59 (1.23 ) Net income $ 2.54 $ 0.28 $ 9.80 $ 4.87 The computation of diluted EPS excludes 0.3 million shares for each of the quarterly and year-to-date periods ended September 28, 2018 and 0.4 million shares and 0.3 million shares for the quarterly and year-to-date periods ended September 29, 2017 , respectively, for share-based payment awards as they were anti-dilutive.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 28, 2018
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. September 28, 2018 December 31, 2017 Description Level 1 (1) Level 2 (2) Level 3 (3) Level 1 (1) Level 2 (2) Level 3 (3) (in millions) Assets Cash equivalents $ 167 $ — $ — $ 310 $ — $ — Derivatives (foreign currency forward contracts) — 4 — — 11 — Total assets $ 167 $ 4 $ — $ 310 $ 11 $ — Liabilities Derivatives (foreign currency forward contracts) $ — $ 6 $ — $ — $ 1 $ — Contingent consideration — — 16 — — 31 Total liabilities $ — $ 6 $ 16 $ — $ 1 $ 31 __________________ (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. The contingent consideration liabilities represent the future potential earn-out payments relating to the acquisitions of MacDonald Humfrey (Automation) Limited, renamed L3 MacDonald Humfrey (MacH), on November 22, 2016, Open Water Power, Inc., renamed L3 Open Water Power, Inc. (Open Water Power), on May 19, 2017 and Latitude Engineering, LLC, renamed L3 Latitude Engineering, Inc. (Latitude Engineering) on June 28, 2018 and the Peak Nano investment. The fair value of the MacH contingent consideration liability, and a portion of the Latitude Engineering 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, and the aggregate revenue of Latitude Engineering as of each year within the four-year period ended December 31, 2021. The significant unobservable inputs used in calculating the fair value of the MacH contingent consideration and a portion of the Latitude Engineering contingent consideration include: (i) projected revenues of the acquired businesses, (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 and a portion of the Latitude Engineering contingent consideration liability is based on the Scenario-Based Method of the income approach using post-acquisition milestone achievements of Open Water Power and Latitude Engineering through December 31, 2020. The significant unobservable inputs used in calculating the fair value of the Open Water Power contingent consideration and a portion of the Latitude Engineering contingent consideration include: (i) timing of achieving the milestones associated with the contingent consideration arrangement, (ii) probabilities of achieving each milestone and (iii) the 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 operating costs and expenses in the unaudited condensed consolidated statements of operations. The Peak Nano contingent consideration liability was recorded at fair value on the acquisition date based on a probability assessment of the likelihood of achieving certain technical milestones on or before August 5, 2018. During the quarter ended September 28, 2018, the Company reduced the fair value of the contingent consideration liability to zero as the technical milestones were not met by the deadline. The fair value of the contingent consideration liability has been reassessed quarterly, and changes reflected within interest and other income, net, in the unaudited condensed consolidated statements of operations. The table below presents the changes to contingent consideration obligations during the year-to-date period ended September 28, 2018 . September 28, 2018 (in millions) Balance at beginning of period $ 31 Acquisitions and investments 10 Cash payments (7 ) Changes in fair value of contingent consideration, net (18 ) Balance at end of period $ 16

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 28, 2018
Investments, All Other Investments [Abstract]
Financial Instruments	Financial Instruments At September 28, 2018 and December 31, 2017 , 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 the 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. September 28, 2018 December 31, 2017 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value (in millions) Senior notes (1) $ 3,320 $ 3,338 $ 3,330 $ 3,502 Foreign currency forward contracts (2) $ (2 ) $ (2 ) $ 10 $ 10 __________________ (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 18 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 28, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
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. Foreign Currency Forward Contracts. 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 Canadian dollar, the U.S. dollar, the Euro, the United Arab Emirates dirham, the British pound and the New Zealand dollar. 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 condensed consolidated 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 AOCI 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. 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 September 28, 2018 . Currency Notional Amounts (in millions) Canadian dollar $ 155 U.S. dollar 141 Euro 97 United Arab Emirates dirham 12 British pound 10 New Zealand dollar 4 Total $ 419 At September 28, 2018 , 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 condensed consolidated balance sheets. September 28, 2018 December 31, 2017 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) $ 3 $ 1 $ 5 $ 1 $ 11 $ — $ 1 $ — Total derivative instruments $ 3 $ 1 $ 5 $ 1 $ 11 $ — $ 1 $ — __________________ (1) See Note 16 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 unaudited condensed consolidated statements of operations were a pre-tax loss of $3 million and pre-tax gain of $2 million for the quarterly periods ended September 28, 2018 and September 29, 2017 , respectively, and a pre-tax loss of $2 million and pre-tax gain of $3 million for the year-to-date period s ended September 28, 2018 and September 29, 2017 , respectively. At September 28, 2018 , the estimated net amount of existing losses that are expected to be reclassified into income within the next 12 months was $3 million .

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 28, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies 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 the matter 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. Amounts recoverable from insurance contracts or third parties are recorded as assets when deemed probable. At September 28, 2018 , 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 the matter set forth below, unless otherwise stated, the Company believes that it is not probable that a loss has been incurred in such matter. With respect to any litigation matter 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 any 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. 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 Postretiremen

Pension and Other Postretirement Benefits	9 Months Ended
	Sep. 28, 2018
Retirement Benefits [Abstract]
Pension and Other Postretirement Benefits	Pension and Other Postretirement Benefits The following table summarizes the components of net periodic benefit cost for the Company’s pension and other postretirement benefit plans. Pension Plans Postretirement Benefit Plans Third Quarter Ended Year-to-Date Ended Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, September 28, September 29, September 28, September 29, (in millions) Components of net periodic benefit cost: Service cost $ 25 $ 22 $ 77 $ 72 $ — $ 1 $ 1 $ 2 Interest cost 36 35 108 106 2 2 4 4 Expected return on plan assets (56 ) (48 ) (168 ) (146 ) (2 ) (1 ) (4 ) (3 ) Amortization of prior service (credits) costs (1 ) 1 (1 ) 1 (1 ) (1 ) (1 ) (1 ) Amortization of net loss (gains) 18 14 55 45 — (1 ) (2 ) (2 ) Curtailment loss (1) — 2 — 2 — — — — Net periodic benefit cost $ 22 $ 26 $ 71 $ 80 $ (1 ) $ — $ (2 ) $ — __________________ (1) During the quarterly period ended September 29, 2017, the Company recognized a $2 million pension curtailment loss related to severance and restructuring activities in the ISRS segment. The components of net periodic benefit cost other than the service cost component are included in interest and other income, net, in the unaudited condensed consolidated statements of operations. Service cost is included in operating costs and expenses in the unaudited condensed consolidated statements of operations. Contributions. The Company contributed cash of $94 million to its pension plans and $4 million to its other postretirement benefit plans during the year-to-date period ended September 28, 2018 . The Company expects to contribute an additional $6 million each to its pension plans and its other postretirement benefit plans during the remainder of 2018 .

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 28, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation During the year-to-date period ended September 28, 2018 , the Company granted stock-based awards under the Amended and Restated 2008 Long Term Performance Plan in the form of stock options, restricted stock units and performance units. The stock-based compensation awards granted during the year-to-date period ended September 28, 2018 are further discussed below. Stock Options. The Company granted 221,886 stock options with a weighted average exercise price of $208.92 per option, which was equal to the closing price 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, Chief Executive Officer and President are also subject to performance-based vesting conditions. The weighted average grant date fair value for the options of $37.72 per option was estimated using the Black-Scholes option-pricing model. The weighted average assumptions used in the valuation model for this grant are presented in the table below. Expected holding period (in years) 5.2 Expected volatility 19.8 % Expected dividend yield 1.8 % Risk-free interest rate 2.7 % Restricted Stock Units. The Company granted 250,105 restricted stock units with a weighted average grant date fair value of $210.12 per share. 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 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-to-date period ended September 28, 2018 , 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). Performance Units. The Company granted 22,325 performance units with a weighted average grant date fair value per unit of $209.91 . The final payout for these units is based on the achievement of pre-determined EPS goals established by the Compensation Committee of the Company’s Board of Directors for the three -year period ending December 31, 2020 . Units earned can range from zero to 200% of the original number of units awarded, which are converted into shares of L3’s common stock.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 28, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Year-to-Date Ended September 28, September 29, (in millions) Interest paid $ 125 $ 120 Income tax payments $ 93 $ 129 Income tax refunds $ 4 $ 14

Segment Information and Disaggr

Segment Information and Disaggregation of Net Sales	9 Months Ended
	Sep. 28, 2018
Segment Reporting [Abstract]
Segment Information and Disaggregation of Net Sales	Segment Information and Disaggregation of Net Sales The Company has three reportable segments, which are described in Note 1 . 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 and certain other items that are excluded by management for purposes of evaluating the operating performance of the Company’s business segments. The tables below present net sales, operating income, depreciation and amortization and total assets by reportable segment. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions) Net Sales: ISRS $ 1,099 $ 968 $ 3,250 $ 2,940 C&NS 745 759 2,270 2,290 Electronic Systems 703 584 2,047 1,839 Elimination of intercompany sales (28 ) (18 ) (94 ) (70 ) Consolidated total $ 2,519 $ 2,293 $ 7,473 $ 6,999 Operating Income: ISRS $ 121 $ 73 $ 321 $ 256 C&NS 69 81 208 277 Electronic Systems 91 78 276 230 Segment total 281 232 805 763 (Loss) gain on sale of the Crestview & TCS Businesses (4 ) — 44 — Merger, acquisition and divestiture related expenses (5 ) — (5 ) — Consolidated total $ 272 $ 232 $ 844 $ 763 Depreciation and amortization: ISRS $ 20 $ 21 $ 64 $ 63 C&NS 15 17 48 49 Electronic Systems 19 17 58 49 Consolidated total $ 54 $ 55 $ 170 $ 161 September 28, December 31, (in millions) Total Assets: ISRS $ 4,813 $ 4,164 C&NS 3,722 3,476 Electronic Systems 4,159 3,939 Corporate 490 709 Assets held for sale — 135 Assets of discontinued operations — 306 Consolidated total $ 13,184 $ 12,729 Disaggregation of Total Net Sales . The Company disaggregates its sales from contracts with customers by end customer, contract type, deliverable type and revenue recognition method for each of its segments, as the Company believes these factors affect the nature, amount, timing and uncertainty of the Company’s revenue and cash flows. Sales by End Customer. Direct sales to the end customer represented approximately 65% of the Company’s consolidated sales for the quarterly period ended September 28, 2018 , and indirect sales as a subcontractor or supplier represented the remaining 35% . Direct sales to the end customer represented approximately 64% of the Company’s consolidated sales for the year-to-date period ended September 28, 2018 , and indirect sales as a subcontractor or supplier represented the remaining 36% . The tables below present total net sales disaggregated by end customer. Third Quarter Ended September 28, 2018 End Customer ISRS C&NS Electronic Systems Consolidated L3 (in millions) Total DoD $ 709 $ 561 $ 309 $ 1,579 Other U.S. Government 48 21 55 124 Total U.S. Government 757 582 364 1,703 Foreign governments (1) 293 71 48 412 Commercial — foreign 8 25 170 203 Commercial — domestic 38 56 107 201 Total $ 1,096 $ 734 $ 689 $ 2,519 Year-to-Date Ended September 28, 2018 End Customer ISRS C&NS Electronic Systems Consolidated L3 (in millions) Total DoD $ 2,227 $ 1,679 $ 968 $ 4,874 Other U.S. Government 108 74 128 310 Total U.S. Government 2,335 1,753 1,096 5,184 Foreign governments (1) 733 242 140 1,115 Commercial — foreign 51 87 503 641 Commercial — domestic 102 161 270 533 Total $ 3,221 $ 2,243 $ 2,009 $ 7,473 __________________ (1) Includes sales under foreign military sales agreements, which are made directly between the U.S. Government and foreign governments. Sales by Contract Type. Generally, the sales price arrangements for the Company’s contracts are either fixed-price, cost-plus or time-and-material type. Fixed-price type contracts generally offer higher profit margin potential than cost-plus type or time-and-material type contracts due to the greater levels of risk assumed on a fixed-price type contract. On a fixed-price type contract, the Company agrees to perform the contractual statement of work for a predetermined sales price. On a cost-plus type contract, the Company is paid its allowable incurred costs plus a profit which can be fixed or variable depending on the contract’s fee arrangement up to predetermined funding levels determined by the customer. Cost-plus type contracts with award and incentive fee provisions are the Company’s primary variable contract fee arrangement. On a time-and-material type contract, the Company is paid on the basis of direct labor hours expended at specified fixed-price hourly rates (that include wages, overhead, allowable general and administrative expenses and profit) and materials at cost. Substantially all of the Company’s cost-plus type contracts and time-and-material type contracts are with U.S. Government customers, while sales to foreign government and commercial customers are generally transacted under fixed-price sales arrangements and are included in the Company’s fixed-price contract type sales. The tables below present total net sales disaggregated by contract type. Third Quarter Ended September 28, 2018 Contract Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Fixed-price (1) $ 697 $ 519 $ 606 $ 1,822 Cost-plus (2) 362 195 75 632 Time-and-material 37 20 8 65 Total sales $ 1,096 $ 734 $ 689 $ 2,519 Year-to-Date Ended September 28, 2018 Contract Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Fixed-price (1) $ 2,046 $ 1,626 $ 1,715 $ 5,387 Cost-plus (2) 1,031 552 270 1,853 Time-and-material 144 65 24 233 Total sales $ 3,221 $ 2,243 $ 2,009 $ 7,473 __________________ (1) Includes fixed-price incentive fee type contracts, which contributed approximately 1% to the Company's total net sales for the quarterly and year-to-date period s ended September 28, 2018 . (2) Includes cost-plus award and incentive fee type contracts, which contributed approximately 2% and 3% to the Company's total net sales for the quarterly and year-to-date period s ended September 28, 2018 , respectively. Sales by Deliverable Type: The tables below present total net sales disaggregated by the type of deliverable, which is determined by the Company at the performance obligation level. Third Quarter Ended September 28, 2018 Sales by Deliverable Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Products $ 712 $ 543 $ 481 $ 1,736 Services 384 191 208 783 Total sales $ 1,096 $ 734 $ 689 $ 2,519 Year-to-Date Ended September 28, 2018 Sales by Deliverable Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Products $ 2,085 $ 1,668 $ 1,415 $ 5,168 Services 1,136 575 594 2,305 Total sales $ 3,221 $ 2,243 $ 2,009 $ 7,473 Revenue Recognition Method: The tables below present total net sales disaggregated based on the revenue recognition method applied. Third Quarter Ended September 28, 2018 Revenue Recognition Method ISRS C&NS Electronic Systems Consolidated L3 (in millions) Cost to cost method $ 813 $ 678 $ 374 $ 1,865 Point in time 220 38 173 431 Output method 18 4 130 152 Billing method 45 14 12 71 Total sales $ 1,096 $ 734 $ 689 $ 2,519 Year-to-Date Ended September 28, 2018 Revenue Recognition Method ISRS C&NS Electronic Systems Consolidated L3 (in millions) Cost to cost method $ 2,456 $ 1,932 $ 1,221 $ 5,609 Point in time 604 238 505 1,347 Output method 47 17 250 314 Billing method 114 56 33 203 Total sales $ 3,221 $ 2,243 $ 2,009 $ 7,473

Severance and Restructuring Rel

Severance and Restructuring Related Costs	9 Months Ended
	Sep. 28, 2018
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 a total of $4 million and $18 million of severance and restructuring related costs with respect to approximately 500 employees during the quarterly and year-to-date periods ended September 28, 2018 , respectively. During the year ended December 31, 2017 , the Company recorded a total of $101 million of severance and restructuring related costs with respect to approximately 1,500 employees. Severance and restructuring related costs are reported within operating costs and expenses on the unaudited condensed consolidated statements of operations. Severance and restructuring related costs incurred by reportable segment are presented in the table below. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions) Reportable Segment ISRS (1) $ 2 $ 15 $ 4 $ 17 C&NS — 17 9 36 Electronic Systems 2 2 5 7 Consolidated $ 4 $ 34 $ 18 $ 60 __________________ (1) The severance and restructuring related costs incurred during the quarterly period ended September 29, 2017 includes $2 million of pension curtailment losses. See Note 20 for additional information. The Company had severance and restructuring related liabilities of $13 million and $23 million included in other current liabilities on the Company’s balance sheets at September 28, 2018 and December 31, 2017 , respectively. The remaining liability balance at September 28, 2018 is expected to be paid primarily by the third quarter of 2019. The table below presents the change to the Company’s severance and restructuring related liability during the year-to-date period ended September 28, 2018 . September 28, 2018 (in millions) Balance at beginning of period $ 23 Additional provisions 18 Cash payments (28 ) Balance at end of period $ 13

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 28, 2018
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event On October 14, 2018, L3 and Harris Corporation (“Harris”) announced an agreement to combine in an all stock merger of equals. Under the terms of the Agreement and Plan of Merger (the “Merger Agreement”) governing the proposed transaction, which was unanimously approved by the boards of directors of both companies, L3 shareholders will receive a fixed exchange ratio of 1.30 shares of Harris common stock for each share of L3 common stock they hold. Upon completion of the merger, Harris shareholders will own approximately 54% and L3 shareholders will own approximately 46% of the combined company, which will be renamed L3 Harris Technologies, Inc. The merger is expected to close in the middle of 2019, subject to customary closing conditions, including the receipt of regulatory approvals and approval by the shareholders of both L3 and Harris.

Condensed Combining Financial I

Condensed Combining Financial Information of L3 and Its Subsidiaries	9 Months Ended
	Sep. 28, 2018
Condensed Financial Information Disclosure [Abstract]
Condensed Combining Financial Information of L3 and Its Subsidiaries	Condensed Combining 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 100% owned domestic subsidiaries (the Guarantor Subsidiaries). See Note 9 to the audited consolidated financial statements for the year ended December 31, 2017 , included in the Company’s Annual Report on Form 10-K 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. The following unaudited 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 September 28, 2018 Current assets: Cash and cash equivalents $ 258 $ 21 $ 251 $ (23 ) $ 507 Billed receivables, net 302 322 276 — 900 Contract assets 612 878 217 — 1,707 Inventories 382 294 235 — 911 Prepaid expenses and other current assets 133 199 78 — 410 Total current assets 1,687 1,714 1,057 (23 ) 4,435 Goodwill 2,124 3,011 1,699 — 6,834 Other assets 695 767 453 — 1,915 Investment in and amounts due from consolidated subsidiaries 6,144 6,695 — (12,839 ) — Total assets $ 10,650 $ 12,187 $ 3,209 $ (12,862 ) $ 13,184 Current liabilities $ 751 $ 900 $ 632 $ (23 ) $ 2,260 Amounts due to consolidated subsidiaries — — 444 (444 ) — Other long-term liabilities 937 791 165 — 1,893 Long-term debt 3,320 — — — 3,320 Total liabilities 5,008 1,691 1,241 (467 ) 7,473 L3 shareholders’ equity 5,642 10,496 1,968 (12,464 ) 5,642 Noncontrolling interests — — — 69 69 Total equity 5,642 10,496 1,968 (12,395 ) 5,711 Total liabilities and equity $ 10,650 $ 12,187 $ 3,209 $ (12,862 ) $ 13,184 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) 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) Condensed Combining Statements of Operations: For the quarter ended September 28, 2018: Total net sales $ 872 $ 1,274 $ 456 $ (83 ) $ 2,519 Total operating costs and expenses (759 ) (1,200 ) (362 ) 83 (2,238 ) Loss on sale of the Crestview & TCS Businesses — (4 ) — — (4 ) Merger, acquisition and divestiture related expenses (5 ) — — — (5 ) Operating income 108 70 94 — 272 Interest expense (40 ) — — — (40 ) Interest and other income, net 14 1 — — 15 Debt retirement charge (21 ) — — — (21 ) Income from continuing operations before income taxes 61 71 94 — 226 Provision for income taxes (6 ) (4 ) (8 ) — (18 ) Equity in net income of consolidated subsidiaries 147 48 — (195 ) — Net income 202 115 86 (195 ) 208 Net income attributable to noncontrolling interests — — — (6 ) (6 ) Net income attributable to L3 $ 202 $ 115 $ 86 $ (201 ) $ 202 Comprehensive income attributable to L3 $ 213 $ 115 $ 83 $ (198 ) $ 213 For the quarter ended September 29, 2017: Total net sales $ 836 $ 1,157 $ 386 $ (86 ) $ 2,293 Total operating costs and expenses (747 ) (1,081 ) (319 ) 86 (2,061 ) Operating income 89 76 67 — 232 Interest expense (41 ) — (1 ) — (42 ) Interest and other income, net 1 — 1 — 2 Income from continuing operations before income taxes 49 76 67 — 192 Provision for income taxes (11 ) (19 ) (16 ) — (46 ) Equity in net income of consolidated subsidiaries 105 34 — (139 ) — Income from continuing operations 143 91 51 (139 ) 146 Income from discontinued operations, net of income taxes (121 ) — — — (121 ) Net income 22 91 51 (139 ) 25 Net income attributable to noncontrolling interests — — — (3 ) (3 ) Net income attributable to L3 $ 22 $ 91 $ 51 $ (142 ) $ 22 Comprehensive income attributable to L3 $ 85 $ 139 $ 101 $ (240 ) $ 85 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) Condensed Combining Statements of Operations: For the year-to-date period ended September 28, 2018: Total net sales $ 2,598 $ 3,841 $ 1,309 $ (275 ) $ 7,473 Total operating costs and expenses (2,300 ) (3,594 ) (1,049 ) 275 (6,668 ) Gain on sale of the Crestview & TCS Businesses — 44 — — 44 Merger, acquisition and divestiture related expenses (5 ) — — — (5 ) Operating income 293 291 260 — 844 Interest expense (124 ) — (1 ) — (125 ) Interest and other income, net 25 2 2 — 29 Debt retirement charge (69 ) — — — (69 ) Income from continuing operations before income taxes 125 293 261 — 679 Provision for income taxes (16 ) (39 ) (35 ) — (90 ) Equity in net income of consolidated subsidiaries 465 141 — (606 ) — Income from continuing operations 574 395 226 (606 ) 589 Income from discontinued operations, net of income tax 206 — — — 206 Net income 780 395 226 (606 ) 795 Net income attributable to noncontrolling interests — — — (15 ) (15 ) Net income attributable to L3 $ 780 $ 395 $ 226 $ (621 ) $ 780 Comprehensive income attributable to L3 $ 768 $ 353 $ 180 $ (533 ) $ 768 For the year-to-date period ended September 29, 2017: Total net sales $ 2,580 $ 3,546 $ 1,136 $ (263 ) $ 6,999 Total operating costs and expenses (2,328 ) (3,226 ) (945 ) 263 (6,236 ) Operating income 252 320 191 — 763 Interest expense (125 ) — (1 ) — (126 ) Interest and other income, net 6 — 2 — 8 Income from continuing operations before income taxes 133 320 192 — 645 Provision for income taxes (30 ) (73 ) (44 ) — (147 ) Equity in net income of consolidated subsidiaries 383 92 — (475 ) — Income from continuing operations 486 339 148 (475 ) 498 Income from discontinued operations, net of income tax (98 ) — — — (98 ) Net income 388 339 148 (475 ) 400 Net income attributable to noncontrolling interests — — — (12 ) (12 ) Net income attributable to L3 $ 388 $ 339 $ 148 $ (487 ) $ 388 Comprehensive income attributable to L3 $ 541 $ 447 $ 271 $ (718 ) $ 541 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) Condensed Combining Statements of Cash Flows For the year-to-date period ended September 28, 2018: Operating activities: Net cash from (used in) operating activities from continuing operations $ 248 $ (30 ) $ 131 $ (7 ) $ 342 Investing activities: Business acquisitions, net of cash acquired (192 ) — (176 ) — (368 ) Proceeds from sale of businesses, net of closing date cash balances 360 175 — — 535 Other investing activities (99 ) (59 ) (35 ) — (193 ) Net cash from (used in) investing activities from continuing operations 69 116 (211 ) — (26 ) Financing activities: Proceeds from sale of senior notes 1,798 — — — 1,798 Repurchases and redemptions of senior notes (1,865 ) — — — (1,865 ) Common stock repurchased (322 ) — — — (322 ) Dividends paid (191 ) — — — (191 ) Other financing activities 82 (81 ) 55 55 111 Net cash (used in) from financing activities from continuing operations (498 ) (81 ) 55 55 (469 ) Effect of foreign currency exchange rate changes on cash — — (9 ) — (9 ) Net increase in cash and cash equivalents of discontinued operations 7 — — — 7 Net (decrease) increase in cash (174 ) 5 (34 ) 48 (155 ) Cash and cash equivalents, beginning of the period 432 16 285 (71 ) 662 Cash and cash equivalents, end of the period $ 258 $ 21 $ 251 $ (23 ) $ 507 For the year-to-date period ended September 29, 2017: Operating activities: Net cash from operating activities from continuing operations $ 248 $ 187 $ 187 $ (41 ) $ 581 Investing activities: Business acquisitions, net of cash acquired (291 ) — — — (291 ) Proceeds from sale of businesses, net of closing date cash balances 17 — 1 — 18 Other investing activities (67 ) (5 ) (19 ) — (91 ) Net cash used in investing activities from continuing operations (341 ) (5 ) (18 ) — (364 ) Financing activities: Common stock repurchased (91 ) — — — (91 ) Dividends paid (178 ) — — — (178 ) Other financing activities 211 (174 ) (137 ) 130 30 Net cash used in financing activities from continuing operations (58 ) (174 ) (137 ) 130 (239 ) Effect of foreign currency exchange rate changes on cash — — 16 — 16 Net increase in cash and cash equivalents of discontinued operations 82 — — — 82 Net (decrease) increase in cash (69 ) 8 48 89 76 Cash and cash equivalents, beginning of the period 262 5 203 (107 ) 363 Cash and cash equivalents, end of the period $ 193 $ 13 $ 251 $ (18 ) $ 439 The Company has revised the reported amounts for L3, Guarantor Subsidiaries, Non-Guarantor Subsidiaries and Eliminations in the Condensed Combining Statements of Operations for the quarterly period ended September 29, 2017 and for the year-to-date period ended September 29, 2017 , to retrospectively reflect: (a) changes in Guarantor Subsidiaries resulting from the elimination of Vertex Aerospace as a guarantor 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 of certain Guarantor Subsidiaries. As a result of the error identification discussed in (c) above, Equity in net income of consolidated subsidiaries and Net income of Guarantor Subsidiaries in the Condensed Combining Statements of Operations for the quarter ended September 29, 2017 and for the year-to-date period ended September 29, 2017 was understated by $34 million and $92 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 is not material to the Company's previously issued financial statements taken as a whole. The impact of the items referred to above to the reported columnar amounts for L3, Guarantor Subsidiaries, Non-Guarantor Subsidiaries and Eliminations are enumerated below. Condensed Combining Statement of Operations ( Third Quarter Ended September 29, 2017 ) As Reported Adjustment As Adjusted L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations (in millions) Total net sales $ 840 $ 1,481 $ 408 $ (83 ) $ (4 ) $ (324 ) $ (22 ) $ (3 ) $ 836 $ 1,157 $ 386 $ (86 ) Total operating costs and expenses (746 ) (1,390 ) (343 ) 83 (1 ) 309 24 3 (747 ) (1,081 ) (319 ) 86 Goodwill impairment charge — (187 ) — — — 187 — — — — — — Operating income (loss) 94 (96 ) 65 — (5 ) 172 2 — 89 76 67 — Interest expense (42 ) — (1 ) — 1 — — — (41 ) — (1 ) — Interest and other income (loss), net 7 — (1 ) — (6 ) — 2 — 1 — 1 — Income (loss) from continuing operations before income taxes 59 (96 ) 63 — (10 ) 172 4 — 49 76 67 — (Provision) benefit for income taxes (12 ) 24 (12 ) — 1 (43 ) (4 ) — (11 ) (19 ) (16 ) — Equity in net (loss) income of consolidated subsidiaries (24 ) — — 24 129 34 — (163 ) 105 34 — (139 ) Income (loss) from continuing operations 23 (72 ) 51 24 120 163 — (163 ) 143 91 51 (139 ) Loss from discontinued operations, net of taxes (1 ) — — — (120 ) — — — (121 ) — — — Net income (loss) 22 (72 ) 51 24 — 163 — (163 ) 22 91 51 (139 ) Net income attributable to noncontrolling interests — — — (3 ) — — — — — — — (3 ) Net income (loss) attributable to L3 $ 22 $ (72 ) $ 51 $ 21 $ — $ 163 $ — $ (163 ) $ 22 $ 91 $ 51 $ (142 ) Comprehensive income (loss) attributable to L3 $ 85 $ (67 ) $ 100 $ (33 ) $ — $ 206 $ 1 $ (207 ) $ 85 $ 139 $ 101 $ (240 ) Condensed Combining Statement of Operations ( Year-to-Date Ended September 29, 2017 ) As Reported Adjustment As Adjusted L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations (in millions) Total net sales $ 2,603 $ 4,500 $ 1,201 $ (257 ) $ (23 ) $ (954 ) $ (65 ) $ (6 ) $ 2,580 $ 3,546 $ 1,136 $ (263 ) Total operating costs and expenses (2,334 ) (4,146 ) (1,009 ) 257 6 920 64 6 (2,328 ) (3,226 ) (945 ) 263 Goodwill impairment charge — (187 ) — — — 187 — — — — — — Operating income 269 167 192 — (17 ) 153 (1 ) — 252 320 191 — Interest expense (126 ) (1 ) (1 ) — 1 1 — — (125 ) — (1 ) — Interest and other income, net 12 — 3 — (6 ) — (1 ) — 6 — 2 — Income from continuing operations before income taxes 155 166 194 — (22 ) 154 (2 ) — 133 320 192 — Provision for income taxes (34 ) (37 ) (43 ) — 4 (36 ) (1 ) — (30 ) (73 ) (44 ) — Equity in net income of consolidated subsidiaries 268 — — (268 ) 115 92 — (207 ) 383 92 — (475 ) Income from continuing operations 389 129 151 (268 ) 97 210 (3 ) (207 ) 486 339 148 (475 ) Loss from discontinued operations, net of taxes (1 ) — — — (97 ) — — — (98 ) — — — Net income 388 129 151 (268 ) — 210 (3 ) (207 ) 388 339 148 (475 ) Net income attributable to noncontrolling interests — — — (12 ) — — — — — — — (12 ) Net income attributable to L3 $ 388 $ 129 $ 151 $ (280 ) $ — $ 210 $ (3 ) $ (207 ) $ 388 $ 339 $ 148 $ (487 ) Comprehensive income attributable to L3 $ 541 $ 134 $ 273 $ (407 ) $ — $ 313 $ (2 ) $ (311 ) $ 541 $ 447 $ 271 $ (718 )

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 28, 2018
Accounting Policies [Abstract]
Principles of Consolidation and Reporting	Principles of Consolidation and Reporting 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 and variable interest entities (VIEs) if the Company is the primary beneficiary. The Company also holds interests in certain VIEs for which it was determined the Company is not the primary beneficiary. 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 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 certain current 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. Certain reclassifications have been made to conform prior-year amounts to the current-year presentation. The unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (SEC). Accordingly, they do not include all of the disclosures required by U.S. GAAP for a complete set of annual audited financial statements. The December 31, 2017 condensed consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by U.S. GAAP. In the opinion of management, all adjustments (consisting of normal and recurring adjustments) considered necessary for a fair statement of the results for the interim periods presented have been included. The results of operations for the interim periods are not necessarily indicative of results for the full year. It is generally the Company’s established practice to close its books for the quarters ending March, June and September on the Friday preceding the end of the calendar quarter. The interim unaudited condensed consolidated financial statements included herein have been prepared and are labeled based on that convention. The Company closes its books for annual periods on December 31 regardless of what day it falls on.
Accounting Estimates	Accounting Estimates The preparation of financial statements in conformity with 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 sales, profit and loss recognition related to performance obligations satisfied over time, fair values of assets acquired and liabilities assumed in business combinations and investments, market values for inventories reported at lower of cost or market, pension and postretirement 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.
Revenue Recognition	Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers, as amended (commonly referred to as ASC 606) using the modified retrospective transition method. The cumulative effect of applying the standard was an increase of $13 million to shareholders' equity as of January 1, 2018. The Company’s statement of operations for the quarterly and year-to-date periods ended September 28, 2018 and the Company’s balance sheet as of September 28, 2018 are presented under ASC 606, while the Company’s statement of operations for the quarterly and year-to-date periods ended September 29, 2017 and the Company’s balance sheet as of December 31, 2017 are presented under ASC 605, Revenue Recognition . See Note 3 for disclosure of the impact of the adoption of ASC 606 on the Company’s statement of operations for the quarterly and year-to-date periods ended September 28, 2018 and balance sheet as of September 28, 2018 and the effect of changes made to the Company’s consolidated balance sheet as of January 1, 2018. A substantial majority of the Company’s consolidated net sales are generated from long-term contracts with customers that require it to design, develop, manufacture, modify, upgrade, test and integrate complex aerospace and electronic equipment and to provide engineering and technical services according to the customers’ specifications. These contracts are primarily with agencies of, and prime system contractors to, the U.S. Government and foreign governments and are generally priced on a fixed-price, cost-plus or time-and-material type basis. Substantially all of the Company's cost-plus and time-and-material type contracts are with the U.S. Government, primarily the DoD. Certain of the Company’s contracts with the U.S. Government are multi-year contracts incrementally funded by the customer. The transaction price on these incrementally funded contracts includes contract value amounts not yet funded by the U.S. Government when the Company has a firm order for the goods or services and it is probable that the customer will fund such amounts. In assessing probability, the Company considers, among other factors, the period of time before contract funding is expected, communication from the customer that indicates funding will be obtained and the Company's history of receiving funding under the current contract or previous similar contracts. The Company also generates sales to a lesser extent from contracts with commercial and government customers for standard product and service offerings, which are priced on a firm fixed basis. See Note 23 for additional information regarding the composition of the Company’s net sales. The Company records sales for a contract when it has the approval and commitment of all parties, the contract identifies the rights of the parties and payment terms, the contract has commercial substance and collectability of the consideration is probable. To determine the proper revenue recognition method, the Company first evaluates each of its contractual arrangements to identify its performance obligations. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer. The majority of the Company’s contracts have a single performance obligation because the promise to transfer the individual good or service is not separately identifiable from other promises within the contract and is, therefore, not distinct. These contractual arrangements either require the use of a highly specialized manufacturing process to provide goods according to customer specifications or represent a bundle of contracted goods and services that are integrated and together represent a combined output, which may include the delivery of multiple units. Some of the Company's contracts have multiple performance obligations, primarily (i) related to the provision of multiple goods or services that have alternative use to the Company or that are not substantially the same or (ii) due to the contract covering multiple phases of the product lifecycle (development and engineering, production, maintenance and support). For contracts with more than one performance obligation, the Company allocates the total transaction price in an amount based on the estimated relative standalone selling prices underlying each performance obligation. In cases where a contract requires a customized good or service, the primary method used to estimate standalone selling price is the expected cost plus a margin approach. In cases where the Company sells a standard product or service offering, the standalone selling price is based on an observable standalone selling price. The majority of the Company's sales are from performance obligations satisfied over time and are primarily with agencies of, and prime system contractors to, the U.S. Government and foreign governments. Sales are recognized over time when control is continuously transferred to the customer during the contract. For U.S. Government contracts, the continuous transfer of control to the customer is supported by contract clauses that provide for (i) progress or performance-based payments or (ii) the unilateral right of the customer to terminate the contract for its convenience, in which case the Company has the right to receive payment for costs incurred plus a reasonable profit for products and services that do not have alternative use to the Company. Foreign government and certain commercial contracts contain similar termination for convenience clauses, or the Company has a legally enforceable right to receive payment for costs incurred and a reasonable profit for products or services that do not have alternative use to the Company. Sales on fixed price and cost-plus type contracts that include performance obligations satisfied over time are generally recorded at amounts equal to the ratio of actual cumulative costs incurred divided by total estimated costs at completion, multiplied by (i) the transaction price, less (ii) the cumulative sales recognized in prior periods (cost-to-cost method). Accounting for the sales and profits on performance obligations for which progress is measured using the cost-to-cost method involves the preparation of estimates of: (1) transaction price and (2) total costs at completion, which is equal to the sum of the actual incurred costs to date on the contract and the estimated costs to complete the contract's statement of work. Incurred costs include labor, material, overhead and, for the Company's U.S. Government contractor businesses, general and administrative (G&A) expenses. Incurred costs represent work performed, which corresponds with and thereby represents the transfer of control to the customer. The estimated profit or loss at completion on a contract is equal to the difference between the transaction price and the total estimated cost at completion. In the case of a contract related to complex aerospace or electronic equipment for which the total estimated costs exceed the total transaction price, a loss arises, and a provision for the entire loss is recorded in the period that the loss becomes evident. The unrecoverable costs on a loss contract that are expected to be incurred in the future periods are presented on the balance sheet as a component of other current liabilities entitled "Estimated cost in excess of estimated contract value to complete contracts in process in a loss position." See Note 10 for additional information. The Company’s contracts give rise to variable consideration, including award and incentive fees, as well as amounts incrementally funded by the U.S. Government, or other provisions that can either increase or decrease the transaction price. Award fees provide for a fee based on actual performance relative to contractually specified performance criteria. Incentive fees provide for a fee based on the relationship between total allowable costs and target costs. Variable consideration may require the Company to exercise significant judgment to determine the total transaction price of the contract. The Company includes variable consideration in the transaction price when there is a basis to reasonably estimate the variable amount it will be entitled to receive and it is probable that a significant reversal in revenue recognized will not be required when the uncertainty is resolved. These estimates are based on historical experience, current and forecasted performance, and the Company’s judgment at the time of the evaluation. Contract modifications routinely occur to account for changes in contract specifications or requirements. In most cases, contract modifications are for goods or services that are not distinct and, therefore, are accounted for as part of the existing contract. Transaction price estimates include additional consideration for submitted contract modifications or claims when the Company believes it has an enforceable right to the modification or claim, the amount can be reliably estimated and its realization is reasonably assured. Amounts representing modifications accounted for as part of the existing contract are included in the transaction price and recognized as an adjustment to sales on a cumulative catch-up basis. The Company’s fixed-price type contracts with the U.S. Government typically allow for progress payments or performance-based payments. Progress payments are billed to the customer as contract costs are incurred at an amount generally equal to 80% of incurred costs. Performance based payments are billed to the customer upon the achievement of predetermined performance milestones at amounts not to exceed 90% of contract price. On contracts with progress or performance-based payments, the customer often retains a small portion of the contract price until satisfactory completion of the contractual statement of work. Since a small portion of the contract price is retained, the Company generally recognizes sales in excess of billings, which are presented as contract assets on the balance sheet. The portion of the contract price retained by the customer is a normal business practice to ensure satisfactory contract completion and, therefore, is not considered a significant financing component. Contract assets also arise from cost-plus type contracts, time-and-material type contracts and fixed-price services 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. For certain fixed-price contracts with foreign governments and commercial customers, the Company receives advance payments. Advanced payments are not considered a significant financing component because they are a negotiated contract term to ensure the customer meets its financial obligation, particularly when there are significant upfront working capital requirements. The Company records a liability for advance payments received in excess of sales recognized, which is presented as a contract liability on the balance sheet. Revisions or adjustments to estimates of the transaction price, estimated costs at completion and estimated profit or loss of a performance obligation 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 or loss estimates 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 contract assets and inventories, and in some cases result in liabilities to complete contracts in a loss position. The aggregate impact of net changes in contract estimates is presented in the table below. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Operating income $ 56 $ 55 $ 172 $ 139 Diluted earnings per share $ 0.54 $ 0.44 $ 1.64 $ 1.12 Net sales recognized from the Company's performance obligations partially satisfied in prior periods were $83 million and $213 million for the quarterly and year-to-date periods ended September 28, 2018 , respectively, and relate to revisions in contract estimates. Sales from performance obligations satisfied at a point in time are typically for standard goods and are recognized when the customer obtains control, which is generally upon delivery and acceptance. The Company also records sales for performance obligations relating to standard services (i.e., maintenance and extended warranties covering standard goods sold by the Company) over time by using output measures of time elapsed to measure progress toward satisfying the performance obligation. Sales on time-and-material type contracts are generally recognized each period based on the amount billable to the customer, which is based on direct labor hours expended multiplied by the contractual fixed rate per hour, plus the actual costs of materials and other direct non-labor costs. The following table presents a summary of the Company’s net sales by revenue recognition method as a percentage of total net sales for the year-to-date period ended September 28, 2018 . % of Total Net Sales Cost to cost method 75 % Point in time 18 % Output method 4 % Billing method 3 % Total 100 % Remaining Performance Obligations On September 28, 2018 , the Company had $11.0 billion of remaining performance obligations, which represents the transaction price of firm orders less inception to date sales recognized. Remaining performance obligations exclude unexercised contract options and potential orders under basic ordering agreements or master-type contracts (i.e., indefinite-delivery, indefinite-quantity). The Company expects to recognize sales relating to existing performance obligations of approximately $2.5 billion during the remainder of 2018, $5.4 billion in 2019, $1.7 billion in 2020 and $1.4 billion in the periods thereafter.
Investments in and Loans to Nonconsolidated Affiliates	Investments in and Loans to Nonconsolidated Affiliates The Company’s investments in nonconsolidated affiliates are primarily accounted for using the equity method of accounting and are carried at cost, plus or minus the Company’s share of net earnings or losses of the investment, subject to certain other adjustments. The cost of equity method investments includes transaction costs of the acquisition. As required by U.S. GAAP, to the extent that there is a basis difference between the cost and the underlying equity in the net assets of an equity investment, the Company allocates such differences between tangible and intangible assets. The Company’s share of net earnings or losses of the investment, inclusive of amortization expense for any basis difference associated with the investment, are presented in interest and other income, net, on the Company’s consolidated statements of operations. Dividends received from the investee reduce the carrying amount of the investment. Due to the timing of receiving financial information from its nonconsolidated affiliates, the Company may record its share of net earnings or losses of such affiliates on a three -month lag basis, with the exception of the amortization expense of any basis difference related to tangible and intangible assets which are recorded currently.

New Accounting Standards Impl_2

New Accounting Standards Implemented (Policies)	9 Months Ended
	Sep. 28, 2018
Accounting Changes and Error Corrections [Abstract]
New Accounting Standards Implemented	Effective January 1, 2018, the Company adopted Financial Accounting Standards Board (FASB) 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, 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 decreased operating income and increased interest and other income, net, each by $4 million and $9 million for the quarterly and year-to-date periods ended September 28, 2018 , respectively, and increased operating income and decreased interest and other income, net, each by $3 million and $6 million for the quarterly and year-to-date periods ended September 29, 2017 , respectively. The adoption of this standard did not impact pre-tax income for the quarterly and year-to-date periods ended September 28, 2018 and September 29, 2017 . In January 2017, the FASB issued ASU 2017-01, Clarifying the Definition of a Business , which provides 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 Company adopted this amendment as of January 1, 2018. The adoption of ASU 2017-01 did not have a material impact on the Company's financial statements for the year-to-date period ended September 28, 2018 . In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , as amended (commonly referred to as ASC 606), which replaces numerous requirements in U.S. GAAP, including industry-specific requirements, and provides companies with a single revenue recognition model for recognizing revenue from contracts with customers and significantly expanded the disclosure requirements for revenue arrangements. The new standard, as amended, was effective for the Company for interim and annual reporting periods beginning on January 1, 2018. As discussed in Note 2 , the Company adopted ASC 606 using the modified retrospective transition method. Results for reporting periods beginning after December 31, 2017 are presented under ASC 606, while prior period comparative information has not been restated and continues to be reported in accordance with ASC 605, Revenue Recognition, the accounting standard in effect for periods ending prior to January 1, 2018. With the adoption of ASC 606, the Company recognizes sales over time by using the cost-to-cost method on most of its (i) contracts that were covered by the contract accounting standards under ASC 605 and (ii) fixed-price type contracts that require it to perform services that are not related to the production of tangible assets. Accordingly, the adoption of ASC 606 primarily impacted certain (i) contracts previously covered by contract accounting standards that recognized revenue using the units-of-delivery method and (ii) fixed-price type contracts for services that are not related to the production of tangible assets that recognized revenue on a straight-line basis over the contractual service period. Based on contracts in process at December 31, 2017, the Company recorded, upon adoption of ASC 606, a net increase to retained earnings of $13 million , which includes the acceleration of net sales of approximately $380 million and the related cost of sales. The adjustment to retained earnings primarily relates to contracts previously accounted for under the units-of-delivery method, which is recognized under ASC 606 earlier in the performance period as costs are incurred, as opposed to when the units are delivered under ASC 605. In accordance with the modified retrospective transition provisions of ASC 606, the Company will not recognize any of the accelerated net sales and related cost of sales at January 1, 2018 in the Company’s statements of operations for any historical or future period. The Company made certain presentation changes to its consolidated balance sheet on January 1, 2018 to comply with ASC 606. The components of contracts in process as reported under ASC 605, which included unbilled contract receivables and inventoried contract costs, have been reclassified as contract assets and inventories, respectively, after certain adjustments described below under ASC 606. The adoption of ASC 606 resulted in an increase in unbilled contract receivables (referred to as contract assets under ASC 606) primarily from converting contracts previously applying the units-of-delivery method to the cost-to-cost method with a corresponding reduction in inventoried contract costs. The remainder of inventoried contract costs, primarily related to work in process not controlled by the Company's customers, were reclassified to inventories. Additionally, under ASC 606, the Company capitalizes costs to fulfill a contract (i.e., non-recurring costs for contract-related activities that do not transfer a good or service to the customer) and costs to obtain a contract (i.e., commissions paid to third-party agents or representatives) to prepaid expense and other current assets or other assets (non-current). The Company amortizes costs to obtain a contract and costs to fulfill a contract in a pattern similar to the recognition of sales on the contracts that the capitalized costs relate to. The Company previously accounted for costs to fulfill a contract either as inventoried contract costs or expensed them as incurred. Costs to obtain a contract were generally expensed as incurred. Advance payments and billings in excess of costs and deferred revenue, previously classified in other current liabilities, have been combined and are presented as contract liabilities. In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . The amendments in this update allow a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act (U.S. Tax Reform). The new standard is effective for the Company beginning on January 1, 2019, with early adoption permitted. The Company will adopt ASU 2018-02 effective January 1, 2019. The Company does not expect the adoption of this standard will have a material effect on its financial position, results of operations or cash flows. In August 2017, the FASB issued ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities . The amendments in this update intend to better align the Company'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 the Company 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 the Company 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 the Company 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 February 2016, the FASB issued ASU 2016-02, Leas es, 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 Company will measure leases commencing after the adoption date based on the present value of the lease payments due over the lease term (as defined in ASU 2016-02). The Company will measure and recognize its existing leases on the date of adoption based on the present value of the remaining minimum lease payments, as defined in existing guidance on accounting for leases. 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. The standard currently allows two transition methods whereby the Company may elect either to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements, with certain practical expedients available, or to initially apply the new leases standard at January 1, 2019 and recognize a cumulative-effect adjustment to the opening balance of retained earnings. The Company expects to adopt the standard as of January 1, 2019, by recognizing a cumulative-effect adjustment to the opening balance of retained earnings at January 1, 2019, in the Company’s Quarterly Report on Form 10-Q for the first quarter of 2019. Progress implementing the new standard to date includes: (1) selecting a lease accounting system, (2) electing to apply the transition practical expedients that allows the Company to rely on historical assessments of whether its contracts contain a lease and to use the same lease classifications applied under existing accounting guidance and (3) accumulating the data required to measure existing leases and prepare required disclosures. While the Company will complete its determination of the impact of adopting this standard on its consolidated financial statements in the first quarter of 2019, the Company does not expect ASU 2016-02 will have a material impact on its results of operations or cash flows. See Note 18 to the audited consolidated financial statements for the year ended December 31, 2017, included in the Company’s Annual Report on Form 10-K for additional information about the Company’s leases, including the future minimum lease payments of the Company's operating leases at December 31, 2017. In addition, the Company is in the process of redrafting its accounting policies and internal controls over financial reporting relating to lease accounting, and drafting the expanded disclosures. Other accounting standard updates effective for interim and annual periods beginning after December 31, 2018 , are not expected to have a material impact on the Company’s financial position, results of operations or cash flows.

Accounting Standards Issued a_2

Accounting Standards Issued and Not Yet Implemented (Policies)	9 Months Ended
	Sep. 28, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Standards Implemented	Effective January 1, 2018, the Company adopted Financial Accounting Standards Board (FASB) 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, 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 decreased operating income and increased interest and other income, net, each by $4 million and $9 million for the quarterly and year-to-date periods ended September 28, 2018 , respectively, and increased operating income and decreased interest and other income, net, each by $3 million and $6 million for the quarterly and year-to-date periods ended September 29, 2017 , respectively. The adoption of this standard did not impact pre-tax income for the quarterly and year-to-date periods ended September 28, 2018 and September 29, 2017 . In January 2017, the FASB issued ASU 2017-01, Clarifying the Definition of a Business , which provides 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 Company adopted this amendment as of January 1, 2018. The adoption of ASU 2017-01 did not have a material impact on the Company's financial statements for the year-to-date period ended September 28, 2018 . In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , as amended (commonly referred to as ASC 606), which replaces numerous requirements in U.S. GAAP, including industry-specific requirements, and provides companies with a single revenue recognition model for recognizing revenue from contracts with customers and significantly expanded the disclosure requirements for revenue arrangements. The new standard, as amended, was effective for the Company for interim and annual reporting periods beginning on January 1, 2018. As discussed in Note 2 , the Company adopted ASC 606 using the modified retrospective transition method. Results for reporting periods beginning after December 31, 2017 are presented under ASC 606, while prior period comparative information has not been restated and continues to be reported in accordance with ASC 605, Revenue Recognition, the accounting standard in effect for periods ending prior to January 1, 2018. With the adoption of ASC 606, the Company recognizes sales over time by using the cost-to-cost method on most of its (i) contracts that were covered by the contract accounting standards under ASC 605 and (ii) fixed-price type contracts that require it to perform services that are not related to the production of tangible assets. Accordingly, the adoption of ASC 606 primarily impacted certain (i) contracts previously covered by contract accounting standards that recognized revenue using the units-of-delivery method and (ii) fixed-price type contracts for services that are not related to the production of tangible assets that recognized revenue on a straight-line basis over the contractual service period. Based on contracts in process at December 31, 2017, the Company recorded, upon adoption of ASC 606, a net increase to retained earnings of $13 million , which includes the acceleration of net sales of approximately $380 million and the related cost of sales. The adjustment to retained earnings primarily relates to contracts previously accounted for under the units-of-delivery method, which is recognized under ASC 606 earlier in the performance period as costs are incurred, as opposed to when the units are delivered under ASC 605. In accordance with the modified retrospective transition provisions of ASC 606, the Company will not recognize any of the accelerated net sales and related cost of sales at January 1, 2018 in the Company’s statements of operations for any historical or future period. The Company made certain presentation changes to its consolidated balance sheet on January 1, 2018 to comply with ASC 606. The components of contracts in process as reported under ASC 605, which included unbilled contract receivables and inventoried contract costs, have been reclassified as contract assets and inventories, respectively, after certain adjustments described below under ASC 606. The adoption of ASC 606 resulted in an increase in unbilled contract receivables (referred to as contract assets under ASC 606) primarily from converting contracts previously applying the units-of-delivery method to the cost-to-cost method with a corresponding reduction in inventoried contract costs. The remainder of inventoried contract costs, primarily related to work in process not controlled by the Company's customers, were reclassified to inventories. Additionally, under ASC 606, the Company capitalizes costs to fulfill a contract (i.e., non-recurring costs for contract-related activities that do not transfer a good or service to the customer) and costs to obtain a contract (i.e., commissions paid to third-party agents or representatives) to prepaid expense and other current assets or other assets (non-current). The Company amortizes costs to obtain a contract and costs to fulfill a contract in a pattern similar to the recognition of sales on the contracts that the capitalized costs relate to. The Company previously accounted for costs to fulfill a contract either as inventoried contract costs or expensed them as incurred. Costs to obtain a contract were generally expensed as incurred. Advance payments and billings in excess of costs and deferred revenue, previously classified in other current liabilities, have been combined and are presented as contract liabilities. In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . The amendments in this update allow a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act (U.S. Tax Reform). The new standard is effective for the Company beginning on January 1, 2019, with early adoption permitted. The Company will adopt ASU 2018-02 effective January 1, 2019. The Company does not expect the adoption of this standard will have a material effect on its financial position, results of operations or cash flows. In August 2017, the FASB issued ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities . The amendments in this update intend to better align the Company'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 the Company 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 the Company 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 the Company 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 February 2016, the FASB issued ASU 2016-02, Leas es, 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 Company will measure leases commencing after the adoption date based on the present value of the lease payments due over the lease term (as defined in ASU 2016-02). The Company will measure and recognize its existing leases on the date of adoption based on the present value of the remaining minimum lease payments, as defined in existing guidance on accounting for leases. 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. The standard currently allows two transition methods whereby the Company may elect either to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements, with certain practical expedients available, or to initially apply the new leases standard at January 1, 2019 and recognize a cumulative-effect adjustment to the opening balance of retained earnings. The Company expects to adopt the standard as of January 1, 2019, by recognizing a cumulative-effect adjustment to the opening balance of retained earnings at January 1, 2019, in the Company’s Quarterly Report on Form 10-Q for the first quarter of 2019. Progress implementing the new standard to date includes: (1) selecting a lease accounting system, (2) electing to apply the transition practical expedients that allows the Company to rely on historical assessments of whether its contracts contain a lease and to use the same lease classifications applied under existing accounting guidance and (3) accumulating the data required to measure existing leases and prepare required disclosures. While the Company will complete its determination of the impact of adopting this standard on its consolidated financial statements in the first quarter of 2019, the Company does not expect ASU 2016-02 will have a material impact on its results of operations or cash flows. See Note 18 to the audited consolidated financial statements for the year ended December 31, 2017, included in the Company’s Annual Report on Form 10-K for additional information about the Company’s leases, including the future minimum lease payments of the Company's operating leases at December 31, 2017. In addition, the Company is in the process of redrafting its accounting policies and internal controls over financial reporting relating to lease accounting, and drafting the expanded disclosures. Other accounting standard updates effective for interim and annual periods beginning after December 31, 2018 , are not expected to have a material impact on the Company’s financial position, results of operations or cash flows.

Basis of Presentation (Tables)

Basis of Presentation (Tables)	9 Months Ended
	Sep. 28, 2018
Accounting Policies [Abstract]
Aggregate Impact of Net Changes in Contract Estimates	The aggregate impact of net changes in contract estimates is presented in the table below. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Operating income $ 56 $ 55 $ 172 $ 139 Diluted earnings per share $ 0.54 $ 0.44 $ 1.64 $ 1.12
Summary of Net Sales by Revenue Recognition Method as Percentage of Total Net Sales	The following table presents a summary of the Company’s net sales by revenue recognition method as a percentage of total net sales for the year-to-date period ended September 28, 2018 . % of Total Net Sales Cost to cost method 75 % Point in time 18 % Output method 4 % Billing method 3 % Total 100 %
Impact of Adoption of New Accounting Pronouncement	The aggregate impact of net changes in contract estimates is presented in the table below. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Operating income $ 56 $ 55 $ 172 $ 139 Diluted earnings per share $ 0.54 $ 0.44 $ 1.64 $ 1.12 The table below presents the cumulative effect of the changes made to the consolidated January 1, 2018 balance sheet due to the adoption of ASC 606. BALANCE SHEET December 31, 2017 As Reported Under ASC 605 Adjustments Due to ASC 606 January 1, 2018 As Adjusted Under ASC 606 (in millions) Assets Current assets: Contract assets $ — $ 1,349 $ 1,349 Contracts in process 1,933 (1,933 ) — Inventories 389 537 926 Prepaid expenses and other current assets 300 17 317 Assets held for sale 135 3 138 Assets of discontinued operations 306 (21 ) 285 Total current assets 4,448 (48 ) 4,400 Other assets 264 49 313 Total assets $ 12,729 $ 1 $ 12,730 Liabilities Current liabilities: Accrued expenses $ 217 $ (13 ) $ 204 Contract liabilities — 565 565 Advance payments and billing in excess of costs incurred 509 (509 ) — Other current liabilities 367 (49 ) 318 Liabilities held for sale 17 (1 ) 16 Liabilities of discontinued operations 226 (23 ) 203 Total current liabilities 2,379 (30 ) 2,349 Deferred income taxes 158 4 162 Other liabilities 398 14 412 Total liabilities 7,578 (12 ) 7,566 Shareholders' Equity Retained earnings 6,659 13 6,672 Total equity $ 5,151 $ 13 $ 5,164 The tables below present the impact of the adoption of ASC 606 on the Company's statement of operations. Third Quarter Ended September 28, 2018 STATEMENT OF OPERATIONS Under ASC 605 Effect of ASC 606 As Reported Under ASC 606 (in millions) Net Sales: Products $ 1,723 $ 13 $ 1,736 Services 772 11 783 Total 2,495 24 2,519 Operating costs and expenses: Cost of sales — Products $ (1,271 ) $ (53 ) $ (1,324 ) Cost of sales — Services (540 ) 22 (518 ) General and administrative expenses (421 ) 25 (396 ) Loss on sale of the Crestview & TCS Businesses (4 ) — (4 ) Merger, acquisition and divestiture related expenses (5 ) — (5 ) Operating income 254 18 272 Income from continuing operations before income taxes 208 18 226 Provision for income taxes (14 ) (4 ) (18 ) Income from continuing operations 194 14 208 Income from discontinued operations, net of income taxes 2 (2 ) — Net income 196 12 208 Net income attributable to L3 $ 190 $ 12 $ 202 Basic earnings per share attributable to common shareholders: Continuing operations $ 2.39 $ 0.18 $ 2.57 Discontinued operations 0.03 (0.03 ) — Basic earnings per share $ 2.42 $ 0.15 $ 2.57 Diluted earnings per share attributable to common shareholders: Continuing operations $ 2.37 $ 0.17 $ 2.54 Discontinued operations 0.02 (0.02 ) — Diluted earnings per share $ 2.39 $ 0.15 $ 2.54 Year-to-Date Ended September 28, 2018 STATEMENT OF OPERATIONS Under ASC 605 Effect of ASC 606 As Reported Under ASC 606 (in millions) Net Sales: Products $ 5,038 $ 130 $ 5,168 Services 2,290 15 2,305 Total 7,328 145 7,473 Operating costs and expenses: Cost of sales — Products $ (3,732 ) $ (132 ) $ (3,864 ) Cost of sales — Services (1,629 ) 1 (1,628 ) General and administrative expenses (1,198 ) 22 (1,176 ) Gain on sale of the Crestview & TCS Businesses 43 1 44 Merger, acquisition and divestiture related expenses (5 ) — (5 ) Operating income 807 37 844 Income from continuing operations before income taxes 642 37 679 Provision for income taxes (81 ) (9 ) (90 ) Income from continuing operations 561 28 589 Income from discontinued operations, net of income taxes 208 (2 ) 206 Net income 769 26 795 Net income attributable to L3 $ 754 $ 26 $ 780 Basic earnings per share attributable to common shareholders: Continuing operations $ 6.96 $ 0.36 $ 7.32 Discontinued operations 2.66 (0.03 ) 2.63 Basic earnings per share $ 9.62 $ 0.33 $ 9.95 Diluted earnings per share attributable to common shareholders: Continuing operations $ 6.86 $ 0.35 $ 7.21 Discontinued operations 2.61 (0.02 ) 2.59 Diluted earnings per share $ 9.47 $ 0.33 $ 9.80 The following table quantifies the impact of adopting ASC 606 on segment net sales and segment operating income for the quarterly and year-to-date periods ended September 28, 2018 . Effect of ASC 606 Third Quarter Ended September 28, 2018 Year-to-Date Ended September 28, 2018 Sales Operating Income Sales Operating Income (in millions) ISRS $ 25 $ 10 $ 47 $ 12 C&NS (18 ) 2 43 12 Electronic Systems 17 6 55 12 Segment totals $ 24 $ 18 $ 145 $ 36 The table below presents the impact of the adoption of ASC 606 on the Company's balance sheet. September 28, 2018 BALANCE SHEET Under Effect of As Reported Under ASC 606 (in millions) Assets Current assets: Contract assets $ — $ 1,707 $ 1,707 Contracts in process 2,237 (2,237 ) — Inventories 406 505 911 Prepaid expenses and other current assets 371 39 410 Total current assets 4,446 (11 ) 4,435 Other assets 298 47 345 Total assets $ 13,148 $ 36 $ 13,184 Liabilities Current liabilities: Accrued expenses $ 288 $ (20 ) $ 268 Contract liabilities — 578 578 Advance payments and billings in excess of costs incurred 536 (536 ) — Other current liabilities 351 (52 ) 299 Total current liabilities 2,290 (30 ) 2,260 Deferred income taxes 209 12 221 Other liabilities 427 15 442 Total liabilities 7,476 (3 ) 7,473 Shareholders' Equity Retained earnings 7,224 39 7,263 Total equity $ 5,672 $ 39 $ 5,711

New Accounting Standards Impl_3

New Accounting Standards Implemented (Tables)	9 Months Ended
	Sep. 28, 2018
Accounting Changes and Error Corrections [Abstract]
Impact of Adoption of New Accounting Pronouncement	The aggregate impact of net changes in contract estimates is presented in the table below. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Operating income $ 56 $ 55 $ 172 $ 139 Diluted earnings per share $ 0.54 $ 0.44 $ 1.64 $ 1.12 The table below presents the cumulative effect of the changes made to the consolidated January 1, 2018 balance sheet due to the adoption of ASC 606. BALANCE SHEET December 31, 2017 As Reported Under ASC 605 Adjustments Due to ASC 606 January 1, 2018 As Adjusted Under ASC 606 (in millions) Assets Current assets: Contract assets $ — $ 1,349 $ 1,349 Contracts in process 1,933 (1,933 ) — Inventories 389 537 926 Prepaid expenses and other current assets 300 17 317 Assets held for sale 135 3 138 Assets of discontinued operations 306 (21 ) 285 Total current assets 4,448 (48 ) 4,400 Other assets 264 49 313 Total assets $ 12,729 $ 1 $ 12,730 Liabilities Current liabilities: Accrued expenses $ 217 $ (13 ) $ 204 Contract liabilities — 565 565 Advance payments and billing in excess of costs incurred 509 (509 ) — Other current liabilities 367 (49 ) 318 Liabilities held for sale 17 (1 ) 16 Liabilities of discontinued operations 226 (23 ) 203 Total current liabilities 2,379 (30 ) 2,349 Deferred income taxes 158 4 162 Other liabilities 398 14 412 Total liabilities 7,578 (12 ) 7,566 Shareholders' Equity Retained earnings 6,659 13 6,672 Total equity $ 5,151 $ 13 $ 5,164 The tables below present the impact of the adoption of ASC 606 on the Company's statement of operations. Third Quarter Ended September 28, 2018 STATEMENT OF OPERATIONS Under ASC 605 Effect of ASC 606 As Reported Under ASC 606 (in millions) Net Sales: Products $ 1,723 $ 13 $ 1,736 Services 772 11 783 Total 2,495 24 2,519 Operating costs and expenses: Cost of sales — Products $ (1,271 ) $ (53 ) $ (1,324 ) Cost of sales — Services (540 ) 22 (518 ) General and administrative expenses (421 ) 25 (396 ) Loss on sale of the Crestview & TCS Businesses (4 ) — (4 ) Merger, acquisition and divestiture related expenses (5 ) — (5 ) Operating income 254 18 272 Income from continuing operations before income taxes 208 18 226 Provision for income taxes (14 ) (4 ) (18 ) Income from continuing operations 194 14 208 Income from discontinued operations, net of income taxes 2 (2 ) — Net income 196 12 208 Net income attributable to L3 $ 190 $ 12 $ 202 Basic earnings per share attributable to common shareholders: Continuing operations $ 2.39 $ 0.18 $ 2.57 Discontinued operations 0.03 (0.03 ) — Basic earnings per share $ 2.42 $ 0.15 $ 2.57 Diluted earnings per share attributable to common shareholders: Continuing operations $ 2.37 $ 0.17 $ 2.54 Discontinued operations 0.02 (0.02 ) — Diluted earnings per share $ 2.39 $ 0.15 $ 2.54 Year-to-Date Ended September 28, 2018 STATEMENT OF OPERATIONS Under ASC 605 Effect of ASC 606 As Reported Under ASC 606 (in millions) Net Sales: Products $ 5,038 $ 130 $ 5,168 Services 2,290 15 2,305 Total 7,328 145 7,473 Operating costs and expenses: Cost of sales — Products $ (3,732 ) $ (132 ) $ (3,864 ) Cost of sales — Services (1,629 ) 1 (1,628 ) General and administrative expenses (1,198 ) 22 (1,176 ) Gain on sale of the Crestview & TCS Businesses 43 1 44 Merger, acquisition and divestiture related expenses (5 ) — (5 ) Operating income 807 37 844 Income from continuing operations before income taxes 642 37 679 Provision for income taxes (81 ) (9 ) (90 ) Income from continuing operations 561 28 589 Income from discontinued operations, net of income taxes 208 (2 ) 206 Net income 769 26 795 Net income attributable to L3 $ 754 $ 26 $ 780 Basic earnings per share attributable to common shareholders: Continuing operations $ 6.96 $ 0.36 $ 7.32 Discontinued operations 2.66 (0.03 ) 2.63 Basic earnings per share $ 9.62 $ 0.33 $ 9.95 Diluted earnings per share attributable to common shareholders: Continuing operations $ 6.86 $ 0.35 $ 7.21 Discontinued operations 2.61 (0.02 ) 2.59 Diluted earnings per share $ 9.47 $ 0.33 $ 9.80 The following table quantifies the impact of adopting ASC 606 on segment net sales and segment operating income for the quarterly and year-to-date periods ended September 28, 2018 . Effect of ASC 606 Third Quarter Ended September 28, 2018 Year-to-Date Ended September 28, 2018 Sales Operating Income Sales Operating Income (in millions) ISRS $ 25 $ 10 $ 47 $ 12 C&NS (18 ) 2 43 12 Electronic Systems 17 6 55 12 Segment totals $ 24 $ 18 $ 145 $ 36 The table below presents the impact of the adoption of ASC 606 on the Company's balance sheet. September 28, 2018 BALANCE SHEET Under Effect of As Reported Under ASC 606 (in millions) Assets Current assets: Contract assets $ — $ 1,707 $ 1,707 Contracts in process 2,237 (2,237 ) — Inventories 406 505 911 Prepaid expenses and other current assets 371 39 410 Total current assets 4,446 (11 ) 4,435 Other assets 298 47 345 Total assets $ 13,148 $ 36 $ 13,184 Liabilities Current liabilities: Accrued expenses $ 288 $ (20 ) $ 268 Contract liabilities — 578 578 Advance payments and billings in excess of costs incurred 536 (536 ) — Other current liabilities 351 (52 ) 299 Total current liabilities 2,290 (30 ) 2,260 Deferred income taxes 209 12 221 Other liabilities 427 15 442 Total liabilities 7,476 (3 ) 7,473 Shareholders' Equity Retained earnings 7,224 39 7,263 Total equity $ 5,672 $ 39 $ 5,711

Acquisitions, Divestitures an_2

Acquisitions, Divestitures and Discontinued Operations (Tables)	9 Months Ended
	Sep. 28, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Components of Pre-tax (Loss) Gain Recognized, Proceeds Received and Net Sales Included in Continuing Operations from Business Divestitures Of Business Divestitures	The table below presents pre-tax (loss) gain recognized, the proceeds received and net sales included in continuing operations from these divestitures. Year-to-Date Ended September 29, 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
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 year-to-date period ended September 28, 2018 and the year ended December 31, 2017 , assuming that the business acquisitions completed during 2018 and 2017 had occurred on January 1, 2017 and January 1, 2016 , 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 2018 and 2017 acquisitions had occurred on January 1, 2017 and January 1, 2016 , respectively. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Pro forma net sales $ 2,536 $ 2,338 $ 7,553 $ 7,134 Pro forma income from continuing operations attributable to L3 $ 204 $ 144 $ 577 $ 486 Pro forma net income attributable to L3 $ 204 $ 23 $ 783 $ 388 Pro forma diluted earnings per share from continuing operations $ 2.57 $ 1.80 $ 7.25 $ 6.10 Pro forma diluted earnings per share $ 2.57 $ 0.29 $ 9.84 $ 4.87
Disposal Groups, Including Discontinued Operations	As discussed in Note 1 , on June 29, 2018, the Company completed the sale of its Vertex Aerospace business. The table below presents the statements of operations data for Vertex Aerospace. 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 Vertex Aerospace’s net assets to the sum of: (1) L3 consolidated total net assets and (2) L3 consolidated total debt. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions) Net sales $ — $ 357 $ 597 $ 1,060 Operating costs and expenses (1) — (524 ) (561 ) (1,191 ) Operating (loss) income from discontinued operations — (167 ) 36 (131 ) Interest expense allocated to discontinued operations — (1 ) (1 ) (1 ) Gain on sale of businesses — — 237 — (Loss) income from discontinued operations before income taxes — (168 ) 272 (132 ) Income tax benefit (expense) — 47 (66 ) 34 (Loss) income from discontinued operations, net of income taxes $ — $ (121 ) $ 206 $ (98 ) __________________ (1) The Company recognized $3 million and $1 million of trailing expenses related to the sale of National Security Solutions for the year-to-date period s ended September 28, 2018 and September 29, 2017 , respectively. The major classes of assets and liabilities that were included in discontinued operations related to Vertex Aerospace are presented in the table below. These balances were classified as current at December 31, 2017 as the sale was expected to be completed within one year and the proceeds are not expected to be used to pay down long-term debt. December 31, (in millions) Assets Current assets $ 284 Property, plant and equipment, net 13 Other intangible assets 7 Other assets 2 Total assets of discontinued operations $ 306 Liabilities Accounts payable, trade $ 63 Other current liabilities 131 Current liabilities 194 Long-term liabilities 32 Total liabilities of discontinued operations $ 226
Schedule Of Results Of Operations Of Business Divestitures	Net sales and income before income taxes for Aviation Jet Services, Coleman and the Display Product Line, 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-to-Date Ended September 29, 2017 (in millions) Net sales $ 10 Income before income taxes $ 2
Assets Held for Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Components of Pre-tax (Loss) Gain Recognized, Proceeds Received and Net Sales Included in Continuing Operations from Business Divestitures Of Business Divestitures	The table below presents Crestview & TCS Businesses ’ results of operations and is included in continuing operations. Year-to-Date Ended September 28, 2018 (in millions) Net Sales $ 64 Gain on sale of businesses $ 44 Income from continuing operations before income taxes $ 47
Disposal Groups, Including Discontinued Operations	The major classes of assets and liabilities included as held for sale related to the Crestview & TCS Businesses are presented in the table below. December 31, (in millions) 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

Contract Assets and Contract _2

Contract Assets and Contract Liabilities (Tables)	9 Months Ended
	Sep. 28, 2018
Revenue from Contract with Customer [Abstract]
Rollforward of Net Contract Assets (Liabilities)	The table below presents the components of net contract assets. September 28, January 1, (in millions) Contract assets $ 1,707 $ 1,349 Contract liabilities — current (578 ) (565 ) Contract liabilities — non-current (31 ) (28 ) Net contract assets $ 1,098 $ 756
Components of Contract Assets	The components of contract assets are presented in the table below. September 28, January 1, (in millions) Unbilled contract receivables, gross $ 2,827 $ 2,232 Unliquidated progress payments and advances (1,120 ) (883 ) Total contract assets $ 1,707 $ 1,349

Contracts in Process (Tables)

Contracts in Process (Tables)	9 Months Ended
	Sep. 28, 2018
Contractors [Abstract]
Components of Contracts in Process	The components of contracts in process are presented in the table below. December 31, (in millions) Unbilled contract receivables, gross $ 1,874 Unliquidated progress payments (761 ) Unbilled contract receivables, net 1,113 Inventoried contract costs, gross 891 Unliquidated progress payments (71 ) Inventoried contract costs, net 820 Total contracts in process $ 1,933
General and Administrative, Independent Research and Development and Bid and Proposal 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 operating costs and expenses by the Company’s U.S. Government contractor businesses for the quarterly and year-to-date periods ended September 29, 2017 . Third Quarter Ended Year-to-Date Ended September 29, 2017 September 29, 2017 (in millions) Amounts included in inventoried contract costs at beginning of the period $ 174 $ 173 Contract costs incurred: IRAD and B&P 88 242 Other G&A 211 610 Total 299 852 Amounts charged to operating costs and expenses (294 ) (846 ) Amounts included in inventoried contract costs at end of the period $ 179 $ 179

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 28, 2018
Inventory Disclosure [Abstract]
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. The Company's inventories at December 31, 2017 were comprised primarily of amounts related to standard products. In addition, the Company classified inventories related to contracts for complex aerospace and electronic equipment and engineering and technical services according to the customers' specifications as inventoried contract costs, which was a component of contracts in process on the consolidated balance sheet at December 31, 2017. See Note 7 for additional information. In accordance with ASC 606, all work in process that customers do not currently control are classified within inventories on the Company's consolidated balance sheet at September 28, 2018 , without regard to whether the goods promised to the customer are standard or customized. September 28, December 31, (in millions) Raw materials, components and sub-assemblies $ 319 $ 184 Work in process 404 98 Finished goods 188 107 Total $ 911 $ 389

Goodwill and Identifiable Int_2

Goodwill and Identifiable Intangible Assets (Tables)	9 Months Ended
	Sep. 28, 2018
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) Goodwill $ 2,504 $ 1,977 $ 2,238 $ 6,719 Accumulated impairment losses (46 ) (15 ) (43 ) (104 ) December 31, 2017 2,458 1,962 2,195 6,615 Business acquisitions (1) 150 65 30 245 Foreign currency translation adjustments (9 ) (4 ) (13 ) (26 ) September 28, 2018 2,599 2,023 2,212 6,834 Goodwill 2,645 2,038 2,255 6,938 Accumulated impairment losses (46 ) (15 ) (43 ) (104 ) $ 2,599 $ 2,023 $ 2,212 $ 6,834 __________________ (1) The increase for the ISRS segment was due to the acquisitions of the Azimuth Security, Linchpin Labs and Applied Defense Solutions businesses and the purchase price allocation adjustments for the Kigre business acquisition. The increase for the C&NS segment was due to the acquisition of the ASV Global business and purchase price allocation adjustments for the Adaptive Methods business acquisition. The increase for the Electronic Systems segment was due to the acquisitions of the Latitude Engineering and C.K. Industrial Engineers businesses and the purchase price allocation adjustments for the G-Air and Doss Aviation business acquisitions.
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. September 28, 2018 December 31, 2017 Weighted 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 16 $ 444 $ 280 $ 164 $ 393 $ 257 $ 136 Technology 9 262 124 138 189 114 75 Other 10 61 15 46 29 14 15 Total subject to amortization 767 419 348 611 385 226 IPR&D indefinite 66 — 66 66 — 66 Total $ 833 $ 419 $ 414 $ 677 $ 385 $ 292
Amortization Expense	The table below presents amortization expense recorded by the Company for its identifiable intangible assets. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, 2018 September 29, 2017 (in millions) Amortization expense $ 10 $ 10 32 30
Estimated Amortization Expense	Based on gross carrying amounts at September 28, 2018 , 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 $ 49 $ 59 $ 52 $ 45 $ 38

Other Current Liabilities and_2

Other Current Liabilities and Other Liabilities (Tables)	9 Months Ended
	Sep. 28, 2018
Other Liabilities Disclosure [Abstract]
Other Current Liabilities	The table below presents the components of other current liabilities. September 28, December 31, (in millions) Other Current Liabilities: Accrued product warranty costs $ 69 $ 69 Estimated costs in excess of estimated contract value to complete contracts in process in a loss position 46 63 Accrued interest 39 43 Estimated contingent purchase price payable for acquired businesses (see Note 16) 5 11 Deferred revenues — 38 Other 140 143 Total other current liabilities $ 299 $ 367
Other Liabilities	The table below presents the components of other liabilities. September 28, December 31, (in millions) Other Liabilities: Non-current income taxes payable (see Note 12) $ 180 $ 164 Deferred compensation 53 49 Notes payable and capital lease obligations 38 16 Contract liabilities (see Note 6) 31 — Accrued workers' compensation 24 23 Accrued product warranty costs 22 30 Estimated contingent purchase price payable for acquired businesses (see Note 16) 11 20 Deferred revenues — 19 Other 83 77 Total other liabilities $ 442 $ 398
Changes in Company's Accrued Product Warranty Costs	The table below presents the changes in the Company’s accrued product warranty costs. Year-to-Date Ended September 28, September 29, (in millions) Accrued product warranty costs: Balance at January 1 $ 99 $ 109 Acquisitions during the period — 3 Accruals for product warranties issued during the period 34 34 Changes to accruals for product warranties existing before January 1 (1 ) — Settlements made during the period (41 ) (52 ) Foreign currency translation adjustments — 1 Balance at end of period $ 91 $ 95

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 28, 2018
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. September 28, December 31, (in millions) Borrowings under Revolving Credit Facility (1) $ — $ — 5.20% Senior Notes due 2019 — 1,000 4.75% Senior Notes due 2020 — 800 4.95% Senior Notes due 2021 650 650 3.85% Senior Notes due 2023 800 — 3.95% Senior Notes due 2024 350 350 3.85% Senior Notes due 2026 550 550 4.40% Senior Notes due 2028 1,000 — Principal amount of long-term debt (2) 3,350 3,350 Unamortized discounts (7 ) (7 ) Deferred debt issue costs (23 ) (13 ) Carrying amount of long-term debt $ 3,320 $ 3,330 __________________ (1) During the year-to-date period ended September 28, 2018 , L3’s aggregate borrowings and repayments under the Credit Facility were $501 million . At September 28, 2018 , L3 had the full availability of its $1 billion Credit Facility. (2) With respect to the Company’s outstanding senior notes, including the senior notes issued on June 6, 2018, upon the occurrence of both a “change in control” (as defined in the indentures governing the senior notes) along with a “change of control triggering event” (generally described as the applicable series of senior notes ceasing to be rated investment grade, 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.
Information Regarding Outstanding Senior Subordinated Notes	On June 6, 2018, L3 issued two series of senior notes, which are unsecured senior obligations of L3. The terms of each series of senior notes are presented in the table below. Note Date of Issuance Amount Issued Discount (1) Net Proceeds (2) Effective Interest Rate Redemption at Treasury Rate (3)(4) (dollars in millions) 3.85% Senior Notes due June 15, 2023 (the 2023 Notes) June 6, 2018 $ 800 $ 2 $ 792 3.89 % 20 bps 4.40% Senior Notes due June 15, 2028 (the 2028 Notes) June 6, 2018 $ 1,000 $ 1 $ 990 4.41 % 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 net cash proceeds of $1,782 million (after deduction of the discount, underwriting expenses and commissions and other related expenses) plus cash on hand were used to fund the concurrent cash tender offers (the Tender Offers) for any and all of $1 billion aggregate principal amount of 5.20% Senior Notes due October 15, 2019 (the 2019 Notes) and $800 million aggregate principal amount of 4.75% Senior Notes due July 15, 2020 (the 2020 Notes) and any related redemption of notes not tendered in the Tender Offers. (3) The 2023 Notes may be redeemed at any time prior to May 15, 2023 (one month prior to maturity), and the 2028 Notes may be redeemed at any time prior to March 15, 2028 (three months prior to maturity), at the option of L3, in whole or in part, at a redemption price equal to the greater of: (i) 100% of the principal amount, or (ii) 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 2023 Notes and the 2028 Notes are redeemed at any time on or after May 15, 2023 and March 15, 2028, respectively, the redemption price would be equal to 100% of the principal amount. (4) Upon the occurrence of a change in control (as defined in the indentures governing the senior notes) along with a “change of control triggering event” (generally described as the applicable series of senior notes ceasing to be rated investment grade, 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 table below summarizes the Tender Offers with respect to the 2019 Notes and the 2020 Notes. Note Settlement Type Date Settled Aggregate Principal Principal Tendered Tender Premium Cash Tendered (1) Interest Total Cash Payments Debt Charge (2) (dollars in millions) 5.20% Senior Notes due 2019 Tender Offer June 6, 2018 $ 1,000 $ 683 103.282 % $ 705 $ 5 $ 710 $ 24 4.75% Senior Notes due 2020 Tender Offer June 6, 2018 $ 800 $ 535 104.092 % $ 557 $ 10 $ 567 $ 24 __________________ (1) Excludes $1 million of tender offer fees. (2) The debt retirement charge includes $1 million of tender offer fees and $3 million which represents the non-cash retirement of associated unamortized debt issue costs and discounts. On June 6, 2018, the Company initiated the redemption of the 2019 Notes and the 2020 Notes that remained outstanding subsequent to the expiration of the Tender Offers. On July 6, 2018, the Company completed the redemption of the 2019 Notes and the 2020 Notes. The terms of the 2019 Notes and the 2020 Notes redemption are presented in the table below. Note Settlement Type Date Settled Principal Redemption Premium Cash Payments Interest Total Cash Payments Debt Charge (1) (dollars in millions) 5.20% Senior Notes due 2019 Redemption July 6, 2018 $ 317 103.048 % $ 327 $ 4 $ 331 $ 10 4.75% Senior Notes due 2020 Redemption July 6, 2018 $ 265 103.818 % $ 275 $ 6 $ 281 $ 11 __________________ (1) The debt retirement charge includes $1 million which represents the non-cash retirement of associated unamortized debt issue costs and discounts.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive (Loss) Income (AOCI) (Tables)	9 Months Ended
	Sep. 28, 2018
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 gains (losses) on hedging instruments Unrecognized (losses) gains and prior service cost, net Total accumulated other comprehensive loss (in millions) Balance at December 31, 2017 $ (54 ) $ 9 $ (646 ) $ (691 ) Other comprehensive loss before reclassifications, net of tax (42 ) (11 ) — (53 ) Amounts reclassified from AOCI, net of tax — 2 39 41 Net current period other comprehensive (loss) income (42 ) (9 ) 39 (12 ) Balance at September 28, 2018 $ (96 ) $ — $ (607 ) $ (703 ) Balance at December 31, 2016 $ (178 ) $ 6 $ (554 ) $ (726 ) Other comprehensive income before reclassifications, net of tax 120 8 — 128 Amounts reclassified from AOCI, net of tax — (2 ) 27 25 Net current period other comprehensive income 120 6 27 153 Balance at September 29, 2017 $ (58 ) $ 12 $ (527 ) $ (573 )
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 Unaudited Condensed Consolidated Statements of Operations Third Quarter Ended Year-to-Date Ended Details About AOCI Components September 28, September 29, September 28, September 29, (in millions) (Loss) gain on hedging instruments $ (3 ) $ 2 $ (2 ) $ 3 Cost of sales-products (3 ) 2 (2 ) 3 Income from continuing operations before income taxes — (1 ) — (1 ) Provision for income taxes $ (3 ) $ 1 $ (2 ) $ 2 Income from continuing operations Amortization of defined benefit pension and postretirement items: Net loss (b) $ (16 ) $ (13 ) $ (51 ) $ (43 ) Income from continuing operations before income taxes 4 5 12 16 Provision for income taxes $ (12 ) $ (8 ) $ (39 ) $ (27 ) Income from continuing operations Total reclassification for the period $ (15 ) $ (7 ) $ (41 ) $ (25 ) Income from continuing operations __________________ (a) Amounts in parenthesis indicate charges to the unaudited condensed 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 20 for additional information).

L3's Earnings Per Common Share

L3's Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 28, 2018
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. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions, except per share data) Reconciliation of net income: Net income $ 208 $ 25 $ 795 $ 400 Net income from continuing operations attributable to noncontrolling interests (6 ) (3 ) (15 ) (12 ) Net income attributable to L3’s common shareholders $ 202 $ 22 $ 780 $ 388 Earnings (loss) attributable to L3’s common shareholders: Continuing operations $ 202 $ 143 $ 574 $ 486 Discontinued operations, net of income tax — (121 ) 206 (98 ) Net income attributable to L3’s common shareholders $ 202 $ 22 $ 780 $ 388 Earnings per share attributable to L3’s common shareholders: Basic: Weighted average common shares outstanding 78.5 78.2 78.4 78.0 Basic earnings (loss) per share: Continuing operations $ 2.57 $ 1.83 $ 7.32 $ 6.23 Discontinued operations, net of income tax — (1.55 ) 2.63 (1.26 ) Net income $ 2.57 $ 0.28 $ 9.95 $ 4.97 Diluted: Common and potential common shares: Weighted average common shares outstanding 78.5 78.2 78.4 78.0 Effect of dilutive securities 0.9 1.6 1.2 1.6 Common and potential common shares 79.4 79.8 79.6 79.6 Diluted earnings (loss) per share: Continuing operations $ 2.54 $ 1.79 $ 7.21 $ 6.10 Discontinued operations, net of income tax — (1.51 ) 2.59 (1.23 ) Net income $ 2.54 $ 0.28 $ 9.80 $ 4.87

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 28, 2018
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. September 28, 2018 December 31, 2017 Description Level 1 (1) Level 2 (2) Level 3 (3) Level 1 (1) Level 2 (2) Level 3 (3) (in millions) Assets Cash equivalents $ 167 $ — $ — $ 310 $ — $ — Derivatives (foreign currency forward contracts) — 4 — — 11 — Total assets $ 167 $ 4 $ — $ 310 $ 11 $ — Liabilities Derivatives (foreign currency forward contracts) $ — $ 6 $ — $ — $ 1 $ — Contingent consideration — — 16 — — 31 Total liabilities $ — $ 6 $ 16 $ — $ 1 $ 31 __________________ (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.
Changes to Contingent Consideration Obligations	The table below presents the changes to contingent consideration obligations during the year-to-date period ended September 28, 2018 . September 28, 2018 (in millions) Balance at beginning of period $ 31 Acquisitions and investments 10 Cash payments (7 ) Changes in fair value of contingent consideration, net (18 ) Balance at end of period $ 16

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 28, 2018
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. September 28, 2018 December 31, 2017 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value (in millions) Senior notes (1) $ 3,320 $ 3,338 $ 3,330 $ 3,502 Foreign currency forward contracts (2) $ (2 ) $ (2 ) $ 10 $ 10 __________________ (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 18 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts.

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 28, 2018
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 September 28, 2018 . Currency Notional Amounts (in millions) Canadian dollar $ 155 U.S. dollar 141 Euro 97 United Arab Emirates dirham 12 British pound 10 New Zealand dollar 4 Total $ 419
Location of Company's Derivative Instruments Recorded at Fair Value on the Condensed Consolidated Balance Sheets	The table below presents the location of the Company’s derivative instruments recorded at fair value on the condensed consolidated balance sheets. September 28, 2018 December 31, 2017 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) $ 3 $ 1 $ 5 $ 1 $ 11 $ — $ 1 $ — Total derivative instruments $ 3 $ 1 $ 5 $ 1 $ 11 $ — $ 1 $ — __________________ (1) See Note 16 for a description of the fair value hierarchy related to the Company’s foreign currency forward contracts.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 28, 2018
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost	The following table summarizes the components of net periodic benefit cost for the Company’s pension and other postretirement benefit plans. Pension Plans Postretirement Benefit Plans Third Quarter Ended Year-to-Date Ended Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, September 28, September 29, September 28, September 29, (in millions) Components of net periodic benefit cost: Service cost $ 25 $ 22 $ 77 $ 72 $ — $ 1 $ 1 $ 2 Interest cost 36 35 108 106 2 2 4 4 Expected return on plan assets (56 ) (48 ) (168 ) (146 ) (2 ) (1 ) (4 ) (3 ) Amortization of prior service (credits) costs (1 ) 1 (1 ) 1 (1 ) (1 ) (1 ) (1 ) Amortization of net loss (gains) 18 14 55 45 — (1 ) (2 ) (2 ) Curtailment loss (1) — 2 — 2 — — — — Net periodic benefit cost $ 22 $ 26 $ 71 $ 80 $ (1 ) $ — $ (2 ) $ — __________________ (1) During the quarterly period ended September 29, 2017, the Company recognized a $2 million pension curtailment loss related to severance and restructuring activities in the ISRS segment.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 28, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted Average Assumptions in Valuation Model	The weighted average assumptions used in the valuation model for this grant are presented in the table below. Expected holding period (in years) 5.2 Expected volatility 19.8 % Expected dividend yield 1.8 % Risk-free interest rate 2.7 %

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 28, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Year-to-Date Ended September 28, September 29, (in millions) Interest paid $ 125 $ 120 Income tax payments $ 93 $ 129 Income tax refunds $ 4 $ 14

Segment Information and Disag_2

Segment Information and Disaggregation of Net Sales (Tables)	9 Months Ended
	Sep. 28, 2018
Disaggregation of Revenue [Line Items]
Summary of Segment Information	The tables below present net sales, operating income, depreciation and amortization and total assets by reportable segment. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions) Net Sales: ISRS $ 1,099 $ 968 $ 3,250 $ 2,940 C&NS 745 759 2,270 2,290 Electronic Systems 703 584 2,047 1,839 Elimination of intercompany sales (28 ) (18 ) (94 ) (70 ) Consolidated total $ 2,519 $ 2,293 $ 7,473 $ 6,999 Operating Income: ISRS $ 121 $ 73 $ 321 $ 256 C&NS 69 81 208 277 Electronic Systems 91 78 276 230 Segment total 281 232 805 763 (Loss) gain on sale of the Crestview & TCS Businesses (4 ) — 44 — Merger, acquisition and divestiture related expenses (5 ) — (5 ) — Consolidated total $ 272 $ 232 $ 844 $ 763 Depreciation and amortization: ISRS $ 20 $ 21 $ 64 $ 63 C&NS 15 17 48 49 Electronic Systems 19 17 58 49 Consolidated total $ 54 $ 55 $ 170 $ 161 September 28, December 31, (in millions) Total Assets: ISRS $ 4,813 $ 4,164 C&NS 3,722 3,476 Electronic Systems 4,159 3,939 Corporate 490 709 Assets held for sale — 135 Assets of discontinued operations — 306 Consolidated total $ 13,184 $ 12,729
Revenue by End Customer [Member]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	The tables below present total net sales disaggregated by end customer. Third Quarter Ended September 28, 2018 End Customer ISRS C&NS Electronic Systems Consolidated L3 (in millions) Total DoD $ 709 $ 561 $ 309 $ 1,579 Other U.S. Government 48 21 55 124 Total U.S. Government 757 582 364 1,703 Foreign governments (1) 293 71 48 412 Commercial — foreign 8 25 170 203 Commercial — domestic 38 56 107 201 Total $ 1,096 $ 734 $ 689 $ 2,519 Year-to-Date Ended September 28, 2018 End Customer ISRS C&NS Electronic Systems Consolidated L3 (in millions) Total DoD $ 2,227 $ 1,679 $ 968 $ 4,874 Other U.S. Government 108 74 128 310 Total U.S. Government 2,335 1,753 1,096 5,184 Foreign governments (1) 733 242 140 1,115 Commercial — foreign 51 87 503 641 Commercial — domestic 102 161 270 533 Total $ 3,221 $ 2,243 $ 2,009 $ 7,473 __________________ (1) Includes sales under foreign military sales agreements, which are made directly between the U.S. Government and foreign governments.
Revenue by Contract Type [Member]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	The tables below present total net sales disaggregated by contract type. Third Quarter Ended September 28, 2018 Contract Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Fixed-price (1) $ 697 $ 519 $ 606 $ 1,822 Cost-plus (2) 362 195 75 632 Time-and-material 37 20 8 65 Total sales $ 1,096 $ 734 $ 689 $ 2,519 Year-to-Date Ended September 28, 2018 Contract Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Fixed-price (1) $ 2,046 $ 1,626 $ 1,715 $ 5,387 Cost-plus (2) 1,031 552 270 1,853 Time-and-material 144 65 24 233 Total sales $ 3,221 $ 2,243 $ 2,009 $ 7,473 __________________ (1) Includes fixed-price incentive fee type contracts, which contributed approximately 1% to the Company's total net sales for the quarterly and year-to-date period s ended September 28, 2018 . (2) Includes cost-plus award and incentive fee type contracts, which contributed approximately 2% and 3% to the Company's total net sales for the quarterly and year-to-date period s ended September 28, 2018
Revenue by Deliverable Type [Member]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	The tables below present total net sales disaggregated by the type of deliverable, which is determined by the Company at the performance obligation level. Third Quarter Ended September 28, 2018 Sales by Deliverable Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Products $ 712 $ 543 $ 481 $ 1,736 Services 384 191 208 783 Total sales $ 1,096 $ 734 $ 689 $ 2,519 Year-to-Date Ended September 28, 2018 Sales by Deliverable Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Products $ 2,085 $ 1,668 $ 1,415 $ 5,168 Services 1,136 575 594 2,305 Total sales $ 3,221 $ 2,243 $ 2,009 $ 7,473
Revenue by Revenue Recognition Method [Member]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	The tables below present total net sales disaggregated based on the revenue recognition method applied. Third Quarter Ended September 28, 2018 Revenue Recognition Method ISRS C&NS Electronic Systems Consolidated L3 (in millions) Cost to cost method $ 813 $ 678 $ 374 $ 1,865 Point in time 220 38 173 431 Output method 18 4 130 152 Billing method 45 14 12 71 Total sales $ 1,096 $ 734 $ 689 $ 2,519 Year-to-Date Ended September 28, 2018 Revenue Recognition Method ISRS C&NS Electronic Systems Consolidated L3 (in millions) Cost to cost method $ 2,456 $ 1,932 $ 1,221 $ 5,609 Point in time 604 238 505 1,347 Output method 47 17 250 314 Billing method 114 56 33 203 Total sales $ 3,221 $ 2,243 $ 2,009 $ 7,473

Severance and Restructuring R_2

Severance and Restructuring Related Costs (Tables)	9 Months Ended
	Sep. 28, 2018
Restructuring and Related Activities [Abstract]
Severance and Restructuring Costs Incurred by Reportable Segment	Severance and restructuring related costs incurred by reportable segment are presented in the table below. Third Quarter Ended Year-to-Date Ended September 28, September 29, September 28, September 29, (in millions) Reportable Segment ISRS (1) $ 2 $ 15 $ 4 $ 17 C&NS — 17 9 36 Electronic Systems 2 2 5 7 Consolidated $ 4 $ 34 $ 18 $ 60 __________________ (1) The severance and restructuring related costs incurred during the quarterly period ended September 29, 2017 includes $2 million of pension curtailment losses. See Note 20 for additional information.
Schedule of Restructuring Reserve	The table below presents the change to the Company’s severance and restructuring related liability during the year-to-date period ended September 28, 2018 . September 28, 2018 (in millions) Balance at beginning of period $ 23 Additional provisions 18 Cash payments (28 ) Balance at end of period $ 13

Condensed Combining Financial_2

Condensed Combining Financial Information of L3 and Its Subsidiaries (Tables)	9 Months Ended
	Sep. 28, 2018
Condensed Financial Information Disclosure [Abstract]
Condensed Combining Balance Sheets	The following unaudited 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 September 28, 2018 Current assets: Cash and cash equivalents $ 258 $ 21 $ 251 $ (23 ) $ 507 Billed receivables, net 302 322 276 — 900 Contract assets 612 878 217 — 1,707 Inventories 382 294 235 — 911 Prepaid expenses and other current assets 133 199 78 — 410 Total current assets 1,687 1,714 1,057 (23 ) 4,435 Goodwill 2,124 3,011 1,699 — 6,834 Other assets 695 767 453 — 1,915 Investment in and amounts due from consolidated subsidiaries 6,144 6,695 — (12,839 ) — Total assets $ 10,650 $ 12,187 $ 3,209 $ (12,862 ) $ 13,184 Current liabilities $ 751 $ 900 $ 632 $ (23 ) $ 2,260 Amounts due to consolidated subsidiaries — — 444 (444 ) — Other long-term liabilities 937 791 165 — 1,893 Long-term debt 3,320 — — — 3,320 Total liabilities 5,008 1,691 1,241 (467 ) 7,473 L3 shareholders’ equity 5,642 10,496 1,968 (12,464 ) 5,642 Noncontrolling interests — — — 69 69 Total equity 5,642 10,496 1,968 (12,395 ) 5,711 Total liabilities and equity $ 10,650 $ 12,187 $ 3,209 $ (12,862 ) $ 13,184 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) 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
Condensed Combining Statements of Operations	L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) Condensed Combining Statements of Operations: For the quarter ended September 28, 2018: Total net sales $ 872 $ 1,274 $ 456 $ (83 ) $ 2,519 Total operating costs and expenses (759 ) (1,200 ) (362 ) 83 (2,238 ) Loss on sale of the Crestview & TCS Businesses — (4 ) — — (4 ) Merger, acquisition and divestiture related expenses (5 ) — — — (5 ) Operating income 108 70 94 — 272 Interest expense (40 ) — — — (40 ) Interest and other income, net 14 1 — — 15 Debt retirement charge (21 ) — — — (21 ) Income from continuing operations before income taxes 61 71 94 — 226 Provision for income taxes (6 ) (4 ) (8 ) — (18 ) Equity in net income of consolidated subsidiaries 147 48 — (195 ) — Net income 202 115 86 (195 ) 208 Net income attributable to noncontrolling interests — — — (6 ) (6 ) Net income attributable to L3 $ 202 $ 115 $ 86 $ (201 ) $ 202 Comprehensive income attributable to L3 $ 213 $ 115 $ 83 $ (198 ) $ 213 For the quarter ended September 29, 2017: Total net sales $ 836 $ 1,157 $ 386 $ (86 ) $ 2,293 Total operating costs and expenses (747 ) (1,081 ) (319 ) 86 (2,061 ) Operating income 89 76 67 — 232 Interest expense (41 ) — (1 ) — (42 ) Interest and other income, net 1 — 1 — 2 Income from continuing operations before income taxes 49 76 67 — 192 Provision for income taxes (11 ) (19 ) (16 ) — (46 ) Equity in net income of consolidated subsidiaries 105 34 — (139 ) — Income from continuing operations 143 91 51 (139 ) 146 Income from discontinued operations, net of income taxes (121 ) — — — (121 ) Net income 22 91 51 (139 ) 25 Net income attributable to noncontrolling interests — — — (3 ) (3 ) Net income attributable to L3 $ 22 $ 91 $ 51 $ (142 ) $ 22 Comprehensive income attributable to L3 $ 85 $ 139 $ 101 $ (240 ) $ 85 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) Condensed Combining Statements of Operations: For the year-to-date period ended September 28, 2018: Total net sales $ 2,598 $ 3,841 $ 1,309 $ (275 ) $ 7,473 Total operating costs and expenses (2,300 ) (3,594 ) (1,049 ) 275 (6,668 ) Gain on sale of the Crestview & TCS Businesses — 44 — — 44 Merger, acquisition and divestiture related expenses (5 ) — — — (5 ) Operating income 293 291 260 — 844 Interest expense (124 ) — (1 ) — (125 ) Interest and other income, net 25 2 2 — 29 Debt retirement charge (69 ) — — — (69 ) Income from continuing operations before income taxes 125 293 261 — 679 Provision for income taxes (16 ) (39 ) (35 ) — (90 ) Equity in net income of consolidated subsidiaries 465 141 — (606 ) — Income from continuing operations 574 395 226 (606 ) 589 Income from discontinued operations, net of income tax 206 — — — 206 Net income 780 395 226 (606 ) 795 Net income attributable to noncontrolling interests — — — (15 ) (15 ) Net income attributable to L3 $ 780 $ 395 $ 226 $ (621 ) $ 780 Comprehensive income attributable to L3 $ 768 $ 353 $ 180 $ (533 ) $ 768 For the year-to-date period ended September 29, 2017: Total net sales $ 2,580 $ 3,546 $ 1,136 $ (263 ) $ 6,999 Total operating costs and expenses (2,328 ) (3,226 ) (945 ) 263 (6,236 ) Operating income 252 320 191 — 763 Interest expense (125 ) — (1 ) — (126 ) Interest and other income, net 6 — 2 — 8 Income from continuing operations before income taxes 133 320 192 — 645 Provision for income taxes (30 ) (73 ) (44 ) — (147 ) Equity in net income of consolidated subsidiaries 383 92 — (475 ) — Income from continuing operations 486 339 148 (475 ) 498 Income from discontinued operations, net of income tax (98 ) — — — (98 ) Net income 388 339 148 (475 ) 400 Net income attributable to noncontrolling interests — — — (12 ) (12 ) Net income attributable to L3 $ 388 $ 339 $ 148 $ (487 ) $ 388 Comprehensive income attributable to L3 $ 541 $ 447 $ 271 $ (718 ) $ 541
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-to-date period ended September 28, 2018: Operating activities: Net cash from (used in) operating activities from continuing operations $ 248 $ (30 ) $ 131 $ (7 ) $ 342 Investing activities: Business acquisitions, net of cash acquired (192 ) — (176 ) — (368 ) Proceeds from sale of businesses, net of closing date cash balances 360 175 — — 535 Other investing activities (99 ) (59 ) (35 ) — (193 ) Net cash from (used in) investing activities from continuing operations 69 116 (211 ) — (26 ) Financing activities: Proceeds from sale of senior notes 1,798 — — — 1,798 Repurchases and redemptions of senior notes (1,865 ) — — — (1,865 ) Common stock repurchased (322 ) — — — (322 ) Dividends paid (191 ) — — — (191 ) Other financing activities 82 (81 ) 55 55 111 Net cash (used in) from financing activities from continuing operations (498 ) (81 ) 55 55 (469 ) Effect of foreign currency exchange rate changes on cash — — (9 ) — (9 ) Net increase in cash and cash equivalents of discontinued operations 7 — — — 7 Net (decrease) increase in cash (174 ) 5 (34 ) 48 (155 ) Cash and cash equivalents, beginning of the period 432 16 285 (71 ) 662 Cash and cash equivalents, end of the period $ 258 $ 21 $ 251 $ (23 ) $ 507 For the year-to-date period ended September 29, 2017: Operating activities: Net cash from operating activities from continuing operations $ 248 $ 187 $ 187 $ (41 ) $ 581 Investing activities: Business acquisitions, net of cash acquired (291 ) — — — (291 ) Proceeds from sale of businesses, net of closing date cash balances 17 — 1 — 18 Other investing activities (67 ) (5 ) (19 ) — (91 ) Net cash used in investing activities from continuing operations (341 ) (5 ) (18 ) — (364 ) Financing activities: Common stock repurchased (91 ) — — — (91 ) Dividends paid (178 ) — — — (178 ) Other financing activities 211 (174 ) (137 ) 130 30 Net cash used in financing activities from continuing operations (58 ) (174 ) (137 ) 130 (239 ) Effect of foreign currency exchange rate changes on cash — — 16 — 16 Net increase in cash and cash equivalents of discontinued operations 82 — — — 82 Net (decrease) increase in cash (69 ) 8 48 89 76 Cash and cash equivalents, beginning of the period 262 5 203 (107 ) 363 Cash and cash equivalents, end of the period $ 193 $ 13 $ 251 $ (18 ) $ 439
Revised Amounts for Guarantor Subsidiaries, Non-Guarantor Subsidiaries and Eliminations	The impact of the items referred to above to the reported columnar amounts for L3, Guarantor Subsidiaries, Non-Guarantor Subsidiaries and Eliminations are enumerated below. Condensed Combining Statement of Operations ( Third Quarter Ended September 29, 2017 ) As Reported Adjustment As Adjusted L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations (in millions) Total net sales $ 840 $ 1,481 $ 408 $ (83 ) $ (4 ) $ (324 ) $ (22 ) $ (3 ) $ 836 $ 1,157 $ 386 $ (86 ) Total operating costs and expenses (746 ) (1,390 ) (343 ) 83 (1 ) 309 24 3 (747 ) (1,081 ) (319 ) 86 Goodwill impairment charge — (187 ) — — — 187 — — — — — — Operating income (loss) 94 (96 ) 65 — (5 ) 172 2 — 89 76 67 — Interest expense (42 ) — (1 ) — 1 — — — (41 ) — (1 ) — Interest and other income (loss), net 7 — (1 ) — (6 ) — 2 — 1 — 1 — Income (loss) from continuing operations before income taxes 59 (96 ) 63 — (10 ) 172 4 — 49 76 67 — (Provision) benefit for income taxes (12 ) 24 (12 ) — 1 (43 ) (4 ) — (11 ) (19 ) (16 ) — Equity in net (loss) income of consolidated subsidiaries (24 ) — — 24 129 34 — (163 ) 105 34 — (139 ) Income (loss) from continuing operations 23 (72 ) 51 24 120 163 — (163 ) 143 91 51 (139 ) Loss from discontinued operations, net of taxes (1 ) — — — (120 ) — — — (121 ) — — — Net income (loss) 22 (72 ) 51 24 — 163 — (163 ) 22 91 51 (139 ) Net income attributable to noncontrolling interests — — — (3 ) — — — — — — — (3 ) Net income (loss) attributable to L3 $ 22 $ (72 ) $ 51 $ 21 $ — $ 163 $ — $ (163 ) $ 22 $ 91 $ 51 $ (142 ) Comprehensive income (loss) attributable to L3 $ 85 $ (67 ) $ 100 $ (33 ) $ — $ 206 $ 1 $ (207 ) $ 85 $ 139 $ 101 $ (240 ) Condensed Combining Statement of Operations ( Year-to-Date Ended September 29, 2017 ) As Reported Adjustment As Adjusted L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations (in millions) Total net sales $ 2,603 $ 4,500 $ 1,201 $ (257 ) $ (23 ) $ (954 ) $ (65 ) $ (6 ) $ 2,580 $ 3,546 $ 1,136 $ (263 ) Total operating costs and expenses (2,334 ) (4,146 ) (1,009 ) 257 6 920 64 6 (2,328 ) (3,226 ) (945 ) 263 Goodwill impairment charge — (187 ) — — — 187 — — — — — — Operating income 269 167 192 — (17 ) 153 (1 ) — 252 320 191 — Interest expense (126 ) (1 ) (1 ) — 1 1 — — (125 ) — (1 ) — Interest and other income, net 12 — 3 — (6 ) — (1 ) — 6 — 2 — Income from continuing operations before income taxes 155 166 194 — (22 ) 154 (2 ) — 133 320 192 — Provision for income taxes (34 ) (37 ) (43 ) — 4 (36 ) (1 ) — (30 ) (73 ) (44 ) — Equity in net income of consolidated subsidiaries 268 — — (268 ) 115 92 — (207 ) 383 92 — (475 ) Income from continuing operations 389 129 151 (268 ) 97 210 (3 ) (207 ) 486 339 148 (475 ) Loss from discontinued operations, net of taxes (1 ) — — — (97 ) — — — (98 ) — — — Net income 388 129 151 (268 ) — 210 (3 ) (207 ) 388 339 148 (475 ) Net income attributable to noncontrolling interests — — — (12 ) — — — — — — — (12 ) Net income attributable to L3 $ 388 $ 129 $ 151 $ (280 ) $ — $ 210 $ (3 ) $ (207 ) $ 388 $ 339 $ 148 $ (487 ) Comprehensive income attributable to L3 $ 541 $ 134 $ 273 $ (407 ) $ — $ 313 $ (2 ) $ (311 ) $ 541 $ 447 $ 271 $ (718 )

Description of Business (Detail

Description of Business (Details) $ in Millions	Jun. 29, 2018USD ($)	Sep. 28, 2018USD ($)Segment	Sep. 29, 2017USD ($)	Jun. 29, 2018USD ($)Segment	Sep. 28, 2018USD ($)Segment	Sep. 29, 2017USD ($)	Dec. 31, 2017USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of reportable segments | Segment		3		4	3
Gain on sale of businesses		$ (4)	$ 0		$ 44	$ 0
Gain from discontinued operation	$ 237
Gain from discontinued operation, after tax	180
Total sales		$ 2,519	$ 2,293		7,473	$ 6,999
Vertex Aerospace [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of business, base sales price	540			$ 540
Total sales							$ 1,400
Crestview Aerospace and TCS [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of businesses	44				44
Gain on sale of businesses, after tax	$ 22
Total sales					$ 64

Basis of Presentation - Impact

Basis of Presentation - Impact of Adoption of New Accounting Pronouncement (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment of ASC 606 on January 1, 2018, net of taxes						$ 13
Progress billings as percent of incurred costs (percent)			80.00%
Performance-based billings as percent of contract price, maximum (percent)			90.00%
Operating income	$ 272	$ 232	$ 844	$ 763
Diluted earnings per share (in dollars per share)	$ 2.54	$ 0.28	$ 9.80	$ 4.87
Performance obligations satisfied in prior periods	$ 83		$ 213
Research and development expense	$ 82	$ 75	243	$ 203
Lag basis for reporting income (loss) from nonconsolidated affiliates	3 months
Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income	$ 56	$ 55	$ 172	$ 139
Diluted earnings per share (in dollars per share)	$ 0.54	$ 0.44	$ 1.64	$ 1.12
Shareholders' Equity [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment of ASC 606 on January 1, 2018, net of taxes					$ 13

Basis of Presentation - Remaini

Basis of Presentation - Remaining Performance Obligations (Details) $ in Billions	Sep. 28, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-09-29
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 2.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	5.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	1.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	1.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 11

Basis of Presentation - Summary

Basis of Presentation - Summary of Net Sales by Revenue Recognition Method as Percentage of Total Net Sales (Details)	3 Months Ended
	Sep. 28, 2018
Revenue from Contract with Customer [Abstract]
Cost to cost method	75.00%
Point in time	18.00%
Output method	4.00%
Billing method	3.00%
Total	100.00%

New Accounting Standards Impl_4

New Accounting Standards Implemented (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income	$ (272)	$ (232)	$ (844)	$ (763)
Interest and other income, net	15	2	29	8
Cumulative effect adjustment of ASC 606 on January 1, 2018, net of taxes					$ 13
Accounting Standards Update 2017-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income	4	(3)	9	(6)
Retained Earnings [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest and other income, net	$ 4	$ (3)	$ 9	$ (6)
Cumulative effect adjustment of ASC 606 on January 1, 2018, net of taxes					13
Net Sales [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment of ASC 606 on January 1, 2018, net of taxes					$ 380

New Accounting Standards Impl_5

New Accounting Standards Implemented - Impact of Adoption of ASC 606 (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Contract assets	$ 1,707		$ 1,707		$ 1,349	$ 0
Contracts in process	0		0		0	1,933
Inventories	911		911		926	389
Prepaid expenses and other current assets	410		410		317	300
Assets held for sale	0		0		138	135
Assets of discontinued operations	0		0		285	306
Total current assets	4,435		4,435		4,400	4,448
Other assets	345		345		313	264
Total assets	13,184		13,184		12,730	12,729
Liabilities
Accrued expenses	268		268		204	217
Contract liabilities	578		578		565	0
Advance payments and billings in excess of costs incurred	0		0		0	509
Other current liabilities	299		299		318	367
Liabilities held for sale	0		0		16	17
Liabilities of discontinued operations	0		0		203	226
Total current liabilities	2,260		2,260		2,349	2,379
Deferred income taxes	221		221		162	158
Other liabilities	442		442		412	398
Total liabilities	7,473		7,473		7,566	7,578
Shareholders' Equity
Retained earnings	7,263		7,263		6,672	6,659
Total equity	5,711	$ 5,069	5,711	$ 5,069	5,164	5,151	$ 4,624
Net Sales:
Sales	2,519	2,293	7,473	6,999
Operating costs and expenses:
General and administrative expenses	(396)	(380)	(1,176)	(1,097)
Loss on sale of the Crestview Aerospace and TCS businesses	(4)	0	44	0
Merger, acquisition and divestiture related expenses	(5)	0	(5)	0
Operating income	272	232	844	763
Income from continuing operations before income taxes	226	192	679	645
Provision for income taxes	(18)	(46)	(90)	(147)
Income from continuing operations	208	146	589	498
Loss from discontinued operations, net of income taxes	0	(121)	206	(98)
Net income	208	25	795	400
Net income attributable to L3	$ 202	$ 22	$ 780	$ 388
Basic earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	$ 2.57	$ 1.83	$ 7.32	$ 6.23
Discontinued operations (in dollars per share)	0	(1.55)	2.63	(1.26)
Basic earnings per share (in dollars per share)	2.57	0.28	9.95	4.97
Diluted earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	2.54	1.79	7.21	6.10
Discontinued operations (in dollars per share)	0	(1.51)	2.59	(1.23)
Diluted earnings per share (in dollars per share)	$ 2.54	$ 0.28	$ 9.80	$ 4.87
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Assets
Contract assets	$ 0		$ 0			0
Contracts in process	2,237		2,237			1,933
Inventories	406		406			389
Prepaid expenses and other current assets	371		371			300
Assets held for sale						135
Assets of discontinued operations						306
Total current assets	4,446		4,446			4,448
Other assets	298		298			264
Total assets	13,148		13,148			12,729
Liabilities
Accrued expenses	288		288			217
Contract liabilities	0		0			0
Advance payments and billings in excess of costs incurred	536		536			509
Other current liabilities	351		351			367
Liabilities held for sale						17
Liabilities of discontinued operations						226
Total current liabilities	2,290		2,290			2,379
Deferred income taxes	209		209			158
Other liabilities	427		427			398
Total liabilities	7,476		7,476			7,578
Shareholders' Equity
Retained earnings	7,224		7,224			6,659
Total equity	5,672		5,672			5,151
Net Sales:
Sales	2,495		7,328
Operating costs and expenses:
General and administrative expenses	(421)		(1,198)
Loss on sale of the Crestview Aerospace and TCS businesses	(4)		43
Merger, acquisition and divestiture related expenses	(5)		(5)
Operating income	254		807
Income from continuing operations before income taxes	208		642
Provision for income taxes	(14)		(81)
Income from continuing operations	194		561
Loss from discontinued operations, net of income taxes	2		208
Net income	196		769
Net income attributable to L3	$ 190		$ 754
Basic earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	$ 2.39		$ 6.96
Discontinued operations (in dollars per share)	0.03		2.66
Basic earnings per share (in dollars per share)	2.42		9.62
Diluted earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	2.37		6.86
Discontinued operations (in dollars per share)	0.02		2.61
Diluted earnings per share (in dollars per share)	$ 2.39		$ 9.47
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Assets
Contract assets	$ 1,707		$ 1,707		1,349
Contracts in process	(2,237)		(2,237)		(1,933)
Inventories	505		505		537
Prepaid expenses and other current assets	39		39		17
Assets held for sale					3
Assets of discontinued operations					(21)
Total current assets	(11)		(11)		(48)
Other assets	47		47		49
Total assets	36		36		1
Liabilities
Accrued expenses	(20)		(20)		(13)
Contract liabilities	578		578		565
Advance payments and billings in excess of costs incurred	(536)		(536)		(509)
Other current liabilities	(52)		(52)		(49)
Liabilities held for sale					(1)
Liabilities of discontinued operations					(23)
Total current liabilities	(30)		(30)		(30)
Deferred income taxes	12		12		4
Other liabilities	15		15		14
Total liabilities	(3)		(3)		(12)
Shareholders' Equity
Retained earnings	39		39		13
Total equity	39		39		$ 13
Net Sales:
Sales	24		145
Operating costs and expenses:
General and administrative expenses	25		22
Loss on sale of the Crestview Aerospace and TCS businesses	0		1
Merger, acquisition and divestiture related expenses	0		0
Operating income	18		37
Income from continuing operations before income taxes	18		37
Provision for income taxes	(4)		(9)
Income from continuing operations	14		28
Loss from discontinued operations, net of income taxes	(2)		(2)
Net income	12		26
Net income attributable to L3	$ 12		$ 26
Basic earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	$ 0.18		$ 0.36
Discontinued operations (in dollars per share)	(0.03)		(0.03)
Basic earnings per share (in dollars per share)	0.15		0.33
Diluted earnings (loss) per share attributable to common shareholders:
Continuing operations (in dollars per share)	0.17		0.35
Discontinued operations (in dollars per share)	(0.02)		(0.02)
Diluted earnings per share (in dollars per share)	$ 0.15		$ 0.33
ISRS [Member]
Net Sales:
Sales	$ 1,096		$ 3,221
ISRS [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Net Sales:
Sales	25		47
Operating costs and expenses:
Operating income	10		12
C&NS [Member]
Net Sales:
Sales	734		2,243
C&NS [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Net Sales:
Sales	(18)		43
Operating costs and expenses:
Operating income	2		12
Electronic Systems [Member]
Net Sales:
Sales	689		2,009
Electronic Systems [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Net Sales:
Sales	17		55
Operating costs and expenses:
Operating income	6		12
Operating Segments [Member]
Operating costs and expenses:
Operating income	281	$ 232	805	$ 763
Operating Segments [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Net Sales:
Sales	24		145
Operating costs and expenses:
Operating income	18		36
Operating Segments [Member] | ISRS [Member]
Assets
Total assets	4,813		4,813			4,164
Net Sales:
Sales	1,099	968	3,250	2,940
Operating costs and expenses:
Operating income	121	73	321	256
Operating Segments [Member] | C&NS [Member]
Assets
Total assets	3,722		3,722			3,476
Net Sales:
Sales	745	759	2,270	2,290
Operating costs and expenses:
Operating income	69	81	208	277
Operating Segments [Member] | Electronic Systems [Member]
Assets
Total assets	4,159		4,159			$ 3,939
Net Sales:
Sales	703	584	2,047	1,839
Operating costs and expenses:
Operating income	91	78	276	230
Product [Member]
Net Sales:
Sales	1,736	1,584	5,168	4,868
Operating costs and expenses:
Cost of Goods and services sold	(1,324)	(1,189)	(3,864)	(3,630)
Product [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Net Sales:
Sales	1,723		5,038
Operating costs and expenses:
Cost of Goods and services sold	(1,271)		(3,732)
Product [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Net Sales:
Sales	13		130
Operating costs and expenses:
Cost of Goods and services sold	(53)		(132)
Product [Member] | ISRS [Member]
Net Sales:
Sales	712		2,085
Product [Member] | C&NS [Member]
Net Sales:
Sales	543		1,668
Product [Member] | Electronic Systems [Member]
Net Sales:
Sales	481		1,415
Service [Member]
Net Sales:
Sales	783	709	2,305	2,131
Operating costs and expenses:
Cost of Goods and services sold	(518)	$ (492)	(1,628)	$ (1,509)
Service [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Net Sales:
Sales	772		2,290
Operating costs and expenses:
Cost of Goods and services sold	(540)		(1,629)
Service [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Net Sales:
Sales	11		15
Operating costs and expenses:
Cost of Goods and services sold	22		1
Service [Member] | ISRS [Member]
Net Sales:
Sales	384		1,136
Service [Member] | C&NS [Member]
Net Sales:
Sales	191		575
Service [Member] | Electronic Systems [Member]
Net Sales:
Sales	$ 208		$ 594

Acquisitions and Divestitures,

Acquisitions and Divestitures, Business Acquisitions (Details) £ in Millions, $ in Millions, $ in Millions

Sep. 20, 2018USD ($)

Sep. 18, 2018USD ($)

Sep. 18, 2018GBP (£)

Aug. 31, 2018USD ($)shares

Aug. 31, 2018AUD ($)shares

Jun. 29, 2018USD ($)

Jun. 28, 2018USD ($)

Sep. 28, 2018USD ($)

Sep. 29, 2017USD ($)

Sep. 28, 2018USD ($)

Sep. 29, 2017USD ($)

Aug. 31, 2018AUD ($)

Dec. 31, 2017USD ($)

Business Acquisition [Line Items]

Contingent consideration

$ 16

$ 16

$ 31

Goodwill recognized

6,834

6,834

6,615

Pro forma net sales

2,536

$ 2,338

7,553

$ 7,134

ASV Global LLC [Member]

Business Acquisition [Line Items]

Purchase price

$ 94

C.K. Industrial Engineers Limited [Member]

Business Acquisition [Line Items]

Purchase price

$ 24

£ 18

Cash acquired from acquisition

4

£ 3

Goodwill recognized

$ 11

Applied Defense Solutions [Member]

Business Acquisition [Line Items]

Purchase price

$ 53

Cash acquired from acquisition

$ 1

Goodwill recognized

41

41

L3 Latitude Engineering [Member]

Business Acquisition [Line Items]

Purchase price

$ 15

Contingent consideration

20

Liability for the fair value of contingent consideration at acquisition

5

Kigre, G-Air and Adaptive Methods [Member]

Business Acquisition [Line Items]

Increase to goodwill

7

Azimuth Security and Linchpin Labs [Member]

Business Acquisition [Line Items]

Purchase price

$ 185

$ 249

Cash acquired from acquisition

15

$ 21

Contingent consideration

$ 31

$ 43

L3 common shares issuable in acquisition (shares) | shares

161,087

161,087

Liability for the fair value of contingent consideration at acquisition

$ 6

C&NS [Member]

Business Acquisition [Line Items]

Goodwill recognized

2,023

2,023

1,962

C&NS [Member] | ASV Global LLC [Member]

Business Acquisition [Line Items]

Goodwill recognized

63

Goodwill expected to be tax deductible

20

ISRS [Member]

Business Acquisition [Line Items]

Goodwill recognized

2,599

2,599

2,458

ISRS [Member] | Azimuth Security and Linchpin Labs [Member]

Business Acquisition [Line Items]

Goodwill recognized

108

Goodwill expected to be tax deductible

19

Intangible assets acquired

$ 98

Electronic Systems [Member]

Business Acquisition [Line Items]

Goodwill recognized

$ 2,212

$ 2,212

$ 2,195

Electronic Systems [Member] | L3 Latitude Engineering [Member]

Business Acquisition [Line Items]

Goodwill recognized

14

Goodwill expected to be tax deductible

9

Post-acquisition Performance through December 2021 [Member] | L3 Latitude Engineering [Member]

Business Acquisition [Line Items]

Contingent consideration

15

Post-acquisition Milestone Achievements through December 2020 [Member] | L3 Latitude Engineering [Member]

Business Acquisition [Line Items]

Contingent consideration

$ 5

Technology-related Intangible Assets [Member]

Business Acquisition [Line Items]

Finite lived intangible assets, weighted average amortization period

9 years

Technology-related Intangible Assets [Member] | C&NS [Member] | ASV Global LLC [Member]

Business Acquisition [Line Items]

Intangible assets acquired

$ 30

Finite lived intangible assets, weighted average amortization period

15 years

Technology-related Intangible Assets [Member] | ISRS [Member] | Azimuth Security and Linchpin Labs [Member]

Business Acquisition [Line Items]

Finite lived intangible assets, weighted average amortization period

5 years

5 years

Customer Relationships [Member]

Business Acquisition [Line Items]

Finite lived intangible assets, weighted average amortization period

16 years

Customer Relationships [Member] | ISRS [Member] | Azimuth Security and Linchpin Labs [Member]

Business Acquisition [Line Items]

Finite lived intangible assets, weighted average amortization period

20 years

20 years

Acquisitions and Divestitures_2

Acquisitions and Divestitures, Unaudited Pro Forma Statements of Operations Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Business Acquisition [Line Items]
Pro forma net sales	$ 2,536	$ 2,338	$ 7,553	$ 7,134
Pro forma income from continuing operations attributable to L3	204	144	577	486
Pro forma net income attributable to L3	$ 204	$ 23	$ 783	$ 388
Pro forma diluted earnings per share from continuing operations (in dollars per share)	$ 2.57	$ 1.80	$ 7.25	$ 6.10
Pro forma diluted earnings per share (in dollars per share)	$ 2.57	$ 0.29	$ 9.84	$ 4.87

Acquisitions, Divestitures an_3

Acquisitions, Divestitures and Discontinued Operations Acquisitions and Divestitures, Investments in Unconsolidated Affiliates (Details) - USD ($) $ in Millions	Sep. 28, 2018	Feb. 16, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Contingent consideration	$ 16		$ 31
Goodwill recognized	6,834		$ 6,615
Variable Interest Entity, Not Primary Beneficiary [Member] | Peak Nano [Member]
Schedule of Equity Method Investments [Line Items]
Investment in nonconsolidated affiliate (percent)		25.00%
Purchase price		$ 20
Contingent milestone payment		30
Contingent consideration	$ 0	6
Goodwill recognized		11
IPR&D [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Peak Nano [Member]
Schedule of Equity Method Investments [Line Items]
Indefinite-lived intangible assets		$ 13

Acquisitions and Divestitures_3

Acquisitions and Divestitures, Business Divestitures (Details) £ in Millions, $ in Millions	Jun. 29, 2018USD ($)	Sep. 28, 2018USD ($)	Sep. 29, 2017USD ($)	Sep. 28, 2018USD ($)	Sep. 29, 2017USD ($)	Mar. 01, 2017USD ($)	Mar. 01, 2017GBP (£)	Feb. 24, 2017USD ($)	Feb. 23, 2017USD ($)
Business Acquisition [Line Items]
Pre-Tax (Loss) gain					$ (4)
Proceeds Received					25
Net Sales					10
Net sales		$ 2,519	$ 2,293	$ 7,473	6,999
Gain on sale of businesses		(4)	0	44	0
Income from continuing operations before income taxes		$ 226	$ 192	679	645
Crestview & TCS [Member]
Business Acquisition [Line Items]
Net sales				64
Gain on sale of businesses	$ 44			44
Income from continuing operations before income taxes				$ 47
Aviation Jet Services divestiture [Member]
Business Acquisition [Line Items]
Pre-Tax (Loss) gain					(5)
Proceeds Received					1
Net Sales					1
Sale of business, base sales price						$ 1	£ 1
Coleman divestiture [Member]
Business Acquisition [Line Items]
Pre-Tax (Loss) gain					(3)
Proceeds Received					17
Net Sales					9
Sale of business, base sales price								$ 15
Display Product Line divestiture [Member]
Business Acquisition [Line Items]
Pre-Tax (Loss) gain					4
Proceeds Received					7
Net Sales					0
Sale of business, base sales price									$ 7
Discontinued Operations [Member]
Business Acquisition [Line Items]
Net sales					10
Income from continuing operations before income taxes					$ 2

Acquisitions, Divestitures an_4

Acquisitions, Divestitures and Discontinued Operations Acquisitions and Divestitures, Assets Held for Sale (Details) - USD ($) $ in Millions	Sep. 28, 2018	Jan. 01, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total assets classified as held for sale	$ 0		$ 135
Total liabilities classified as held for sale	$ 0	$ 16	17
Assets Held for Sale [Member] | Crestview & TCS [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
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
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

Acquisitions and Divestitures_4

Acquisitions and Divestitures, Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017	Jan. 01, 2018	Dec. 31, 2017
Discontinued Operations, Income Statement Disclosures [Abstract]
Net Sales				$ 10
Gain on sale of businesses	$ (4)	$ 0	$ 44	0
Income from discontinued operations, net of income taxes	0	(121)	206	(98)
Discontinued Operation, Balance Sheet Disclosures [Abstract]
Total assets of discontinued operations	0		0		$ 285	$ 306
Total liabilities of discontinued operations	0		0		$ 203	226
Vertex Aerospace [Member] | Discontinued Operations [Member]
Discontinued Operations, Income Statement Disclosures [Abstract]
Net Sales	0	357	597	1,060
Operating costs and expenses (1)	0	(524)	(561)	(1,191)
Operating income from discontinued operations	0	(167)	36	(131)
Interest expense allocated to discontinued operations	0	(1)	(1)	(1)
Gain on sale of businesses	0	0	237	0
(Loss) income from discontinued operations before income taxes	0	(168)	272	(132)
Income tax benefit (expense)	0	47	(66)	34
Income from discontinued operations, net of income taxes	$ 0	$ (121)	206	(98)
Trailing expenses related to the sale of NSS			$ 3	$ 1
Discontinued Operation, Balance Sheet Disclosures [Abstract]
Current assets						284
Property, plant and equipment, net						13
Other intangible assets						7
Other assets						2
Total assets of discontinued operations						306
Accounts payable, trade						63
Other current liabilities						131
Current liabilities						194
Long-term liabilities						32
Total liabilities of discontinued operations						$ 226

Contract Assets and Contract _3

Contract Assets and Contract Liabilities - Components of Net Contract Assets (Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 28, 2018	Sep. 28, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Contract assets	$ 1,707	$ 1,707	$ 1,349	$ 0
Contract liabilities — current	(578)	(578)	(565)	0
Contract liabilities — non-current	(31)	(31)	(28)	$ 0
Net contract assets (liabilities)	1,098	1,098	$ 756
Increase in contract assets	358
Increase in contract liability	$ 16
Revenue recognized related to contract liabilities		$ 403

Components of Contract Assets (

Components of Contract Assets (Details) - USD ($) $ in Millions	Sep. 28, 2018	Jan. 01, 2018	Dec. 31, 2017
Contracts Receivable [Abstract]
Unbilled contract receivables, gross	$ 2,827	$ 2,232	$ 1,874
Unliquidated progress payments and advances	(1,120)	(883)	(761)
Total contract assets	$ 1,707	$ 1,349	$ 0

Contracts in Process (Details)

Contracts in Process (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 29, 2017	Sep. 29, 2017	Sep. 28, 2018	Jan. 01, 2018	Dec. 31, 2017
Contractors [Abstract]
Unbilled contract receivables, gross			$ 2,827	$ 2,232	$ 1,874
Unliquidated progress payments			(1,120)	(883)	(761)
Unbilled contract receivables, net					1,113
Inventoried contract costs, gross					891
Unliquidated progress payments					(71)
Inventoried contract costs, net					820
Total contracts in process			$ 0	$ 0	$ 1,933
Summary Of Inventory For Long Term Contracts Or Programs [Roll Forward]
Amounts included in inventoried contract costs at beginning of the period	$ 174	$ 173
Contract Costs Incurred [Abstract]
IRAD and B&P	88	242
Other G&A	211	610
Total	299	852
Amounts charged to operating costs and expenses	(294)	(846)
Amounts included in inventoried contract costs at end of the period	$ 179	$ 179

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2018	Jan. 01, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials, components and sub-assemblies	$ 319		$ 184
Work in process	404		98
Finished goods	188		107
Total	911	$ 926	$ 389
G&A costs included in inventory	53
G&A costs incurred and recorded in inventories	887
G&A costs charged to expense from inventories	$ 891

Goodwill and Identifiable Int_3

Goodwill and Identifiable Intangible Assets - Allocated by Reportable Segment (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 6,938	$ 6,719
Accumulated impairment losses	(104)	(104)
Balance	6,615
Business acquisitions	245
Foreign currency translation adjustments	(26)
Balance	6,834
ISRS [Member]
Goodwill [Line Items]
Goodwill	2,645	2,504
Accumulated impairment losses	(46)	(46)
Balance	2,458
Business acquisitions	150
Foreign currency translation adjustments	(9)
Balance	2,599
C&NS [Member]
Goodwill [Line Items]
Goodwill	2,038	1,977
Accumulated impairment losses	(15)	(15)
Balance	1,962
Business acquisitions	65
Foreign currency translation adjustments	(4)
Balance	2,023
Electronic Systems [Member]
Goodwill [Line Items]
Goodwill	2,255	2,238
Accumulated impairment losses	(43)	$ (43)
Balance	2,195
Business acquisitions	30
Foreign currency translation adjustments	(13)
Balance	$ 2,212

Goodwill and Identifiable Int_4

Goodwill and Identifiable Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite-lived intangible assets, gross carrying amount	$ 767		$ 767		$ 611
Finite-lived intangible assets, accumulated amortization	419		419		385
Finite-lived intangible assets, net carrying amount	348		348		226
Amortization expense	10	$ 10	32	$ 30
Estimated Amortization Expense for Identifiable Intangible Assets [Abstract]
Estimated amortization expense, 2018	49		49
Estimated amortization expense, 2019	59		59
Estimated amortization expense, 2020	52		52
Estimated amortization expense, 2021	45		45
Estimated amortization expense, 2022	38		38
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	833		833		677
Intangible assets, net carrying amount	414		414		292
IPR&D [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	66		$ 66		66
Customer Contractual Relationships [Member]
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite lived intangible assets, weighted average amortization period			16 years
Finite-lived intangible assets, gross carrying amount	444		$ 444		393
Finite-lived intangible assets, accumulated amortization	280		280		257
Finite-lived intangible assets, net carrying amount	164		$ 164		136
Technology [Member]
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite lived intangible assets, weighted average amortization period			9 years
Finite-lived intangible assets, gross carrying amount	262		$ 262		189
Finite-lived intangible assets, accumulated amortization	124		124		114
Finite-lived intangible assets, net carrying amount	138		$ 138		75
Other [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	61		$ 61		29
Finite-lived intangible assets, accumulated amortization	15		15		14
Finite-lived intangible assets, net carrying amount	$ 46		$ 46		$ 15

Other Current Liabilities and_3

Other Current Liabilities and Other Liabilities (Details) - USD ($) $ in Millions	Sep. 28, 2018	Jan. 01, 2018	Dec. 31, 2017
Other Current Liabilities [Abstract]
Accrued product warranty costs	$ 69		$ 69
Estimated costs in excess of estimated contract value to complete contracts in process in a loss position	46		63
Accrued interest	39		43
Estimated contingent purchase price payable for acquired businesses and other investments	5		11
Deferred revenues	0		38
Other	140		143
Total other current liabilities	299	$ 318	367
Other Liabilities [Abstract]
Non-current income taxes payable (see Note 12)	180		164
Deferred compensation	53		49
Notes payable and capital lease obligations	38		16
Contract liabilities	31	28	0
Accrued workers' compensation	24		23
Accrued product warranty costs	22		30
Estimated contingent purchase price payable for acquired businesses	11		20
Deferred revenues	0		19
Other	83		77
Total other liabilities	$ 442	$ 412	$ 398

Other Current Liabilities and_4

Other Current Liabilities and Other Liabilities - Changes in Company's Accrued Product Warranty Costs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Accrued product warranty costs [Roll Forward]:
Balance at January 1	$ 99	$ 109
Acquisitions during the period	0	3
Accruals for product warranties issued during the period	34	34
Changes to accruals for product warranties existing before January 1	(1)	0
Settlements made during the period	(41)	(52)
Foreign currency translation adjustments	0	1
Balance at end of period	$ 91	$ 95

Debt (Details)

Debt (Details) - USD ($) $ in Millions	Jul. 06, 2018	Sep. 28, 2018	Sep. 29, 2017	Jun. 06, 2018	Dec. 31, 2017
Long-term debt, current and noncurrent [Abstract]
Proceeds under the credit facility		$ 501	$ 1,265
Redemption price of senior notes as percentage of principal amount redeemed (percent)		101.00%
Repayments under the credit facility		$ 501	$ 1,265
5.20% Senior Notes due 2019 [Member]
Long-term debt, current and noncurrent [Abstract]
Redemption price of senior notes as percentage of principal amount redeemed (percent)	103.048%
Interest rate on senior notes				5.20%
4.75% Senior Notes due 2020 [Member]
Long-term debt, current and noncurrent [Abstract]
Redemption price of senior notes as percentage of principal amount redeemed (percent)	103.818%
Interest rate on senior notes				4.75%
3.85% Senior Notes due 2023 [Member]
Components of Debt [Abstract]
Unamortized discounts		(2)
4.40% Senior Notes due 2028 [Member]
Components of Debt [Abstract]
Unamortized discounts		(1)
Subsidiaries [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)			(7)
Deferred debt issue costs		(23)			(13)
Carrying amount of long-term debt		3,320			3,330
Subsidiaries [Member] | Revolving Credit Facility [Member]
Long-term debt, current and noncurrent [Abstract]
Proceeds under the credit facility		501
Available borrowings under credit facility		1,000
Repayments under the credit facility		501
Senior Notes [Member] | Subsidiaries [Member] | 5.20% Senior Notes due 2019 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt		$ 0			1,000
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes		5.20%
Debt instrument maturity period		2,019
Senior Notes [Member] | Subsidiaries [Member] | 4.75% Senior Notes due 2020 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt		$ 0			800
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes		4.75%
Debt instrument maturity period		2,020
Senior Notes [Member] | Subsidiaries [Member] | 4.95% Senior Notes due 2021 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt		$ 650			650
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes		4.95%
Debt instrument maturity period		2,021
Senior Notes [Member] | Subsidiaries [Member] | 3.85% Senior Notes due 2023 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt		$ 800			0
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes		3.85%
Debt instrument maturity period		2,023
Senior Notes [Member] | Subsidiaries [Member] | 3.95% Senior Notes due 2024 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt		$ 350			350
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes		3.95%
Debt instrument maturity period		2,024
Senior Notes [Member] | Subsidiaries [Member] | 3.85% Senior Notes due 2026 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt		$ 550			550
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes		3.85%
Debt instrument maturity period		2,026
Senior Notes [Member] | Subsidiaries [Member] | 4.40% Senior Notes due 2028 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt		$ 1,000			$ 0
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes		4.40%
Debt instrument maturity period		2,028

Debt - Debt Outstanding, Senior

Debt - Debt Outstanding, Senior Subordinated Notes (Details) - USD ($)	Jul. 06, 2018	Jun. 06, 2018	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Debt Instrument [Line Items]
Interest					$ 125,000,000	$ 120,000,000
Debt retirement charge			$ (21,000,000)	$ 0	$ (69,000,000)	$ 0
Redemption price of senior notes as percentage of principal amount redeemed (percent)					101.00%
3.85% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Date of Issuance		Jun. 6, 2018
Amount Issued			800,000,000		$ 800,000,000
Discount			$ 2,000,000		2,000,000
Net Cash Proceeds(2)					$ 792,000,000
Effective Interest Rate			3.89%		3.89%
Redemption at Treasury Rate(3)(4)		0.20%
4.40% Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Date of Issuance		Jun. 6, 2018
Amount Issued			$ 1,000,000,000		$ 1,000,000,000
Discount			$ 1,000,000		1,000,000
Net Cash Proceeds(2)					$ 990,000,000
Effective Interest Rate			4.41%		4.41%
Redemption at Treasury Rate(3)(4)		0.25%
Notes due 2023 and 2028 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Debt		$ 1,782,000,000
5.20% Senior Notes due 2019 [Member]
Debt Instrument [Line Items]
Interest rate on senior notes		5.20%
Aggregate principal included in tender offer		$ 1,000,000,000
Interest	$ 4,000,000
Debt retirement charge	$ 10,000,000
Redemption Date	Jul. 6, 2018				Jul. 6, 2018
Aggregate Amount, Redemption	$ 317,000,000
Redemption price of senior notes as percentage of principal amount redeemed (percent)	103.048%
Redemption Cash Payments	$ 327,000,000
Total Cash Payments for Redemptions	331,000,000
4.75% Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Interest rate on senior notes		4.75%
Aggregate principal included in tender offer		$ 800,000,000
Interest	6,000,000
Debt retirement charge	$ 11,000,000
Redemption Date	Jul. 6, 2018				Jul. 6, 2018
Aggregate Amount, Redemption	$ 265,000,000
Redemption price of senior notes as percentage of principal amount redeemed (percent)	103.818%
Redemption Cash Payments	$ 275,000,000
Total Cash Payments for Redemptions	281,000,000
5.20% Senior Notes due 2019, Settled under Tender Offers [Member]
Debt Instrument [Line Items]
Tender Offer Date		Jun. 6, 2018
Aggregate principal included in tender offer		$ 1,000,000,000
Principal Tendered		$ 683,000,000
Tender Premium		103.282%
Cash Tendered		$ 705,000,000
Interest		5,000,000
Total Cash Payments Tendered		710,000,000
Debt retirement charge		$ 24,000,000
4.75% Senior Notes due 2020, Settled under Tender Offers [Member]
Debt Instrument [Line Items]
Tender Offer Date		Jun. 6, 2018
Aggregate principal included in tender offer		$ 800,000,000
Principal Tendered		$ 535,000,000
Tender Premium		104.092%
Cash Tendered		$ 557,000,000
Interest		10,000,000
Total Cash Payments Tendered		567,000,000
Debt retirement charge		24,000,000
Notes Settled under Tender Offers [Member]
Debt Instrument [Line Items]
Tender offer fees included in debt retirement charge		1,000,000
Non-cash portion of debt retirement charge		$ 3,000,000
Redemption of Senior Notes [Member]
Debt Instrument [Line Items]
Non-cash portion of debt retirement charge	$ 1,000,000
Minimum [Member] | Prior to May 15, 2023 and March 15, 2028 [Member]
Debt Instrument [Line Items]
Redemption price of senior notes as percentage of principal amount redeemed (percent)					100.00%
Minimum [Member] | On or After May 15, 2023 and March 15, 2028 [Member]
Debt Instrument [Line Items]
Redemption price of senior notes as percentage of principal amount redeemed (percent)					100.00%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Reduction in tax provision due to lapses in statutes of limitations	$ 14
Preliminary net tax benefit	$ (3)		$ 82		$ 79
Estimated tax benefit related to remeasurement of deferred taxes			100
Estimated tax provision related to Toll Charge			$ 18
Effective tax rate	8.00%	24.00%	13.30%	22.80%
Anticipated decrease in unrecognized tax benefits over the next 12 months	$ 32		$ 32
Accrued potential interest included within current and non-current income taxes payable	16		16		15
Accrued potential interest included within current and non-current income taxes payable, after income taxes	12		12		11
Potential penalties	$ 9		$ 9		$ 8

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive (Loss) Income (AOCI), Summary of AOCI Balances Including Amounts Reclassified from AOCI into Net Income (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	$ 5,083
Other comprehensive (loss) income before reclassifications, net of tax	(53)	$ 128
Amounts reclassified from AOCI, net of tax	41	25
Net current period other comprehensive (loss) income	(12)	153
Ending Balance	5,642
Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(691)	(726)
Ending Balance	(703)	(573)
Foreign Currency Translation [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(54)	(178)
Other comprehensive (loss) income before reclassifications, net of tax	(42)	120
Amounts reclassified from AOCI, net of tax	0	0
Net current period other comprehensive (loss) income	(42)	120
Ending Balance	(96)	(58)
Unrealized Gains (Losses) on Hedging Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	9	6
Other comprehensive (loss) income before reclassifications, net of tax	(11)	8
Amounts reclassified from AOCI, net of tax	2	(2)
Net current period other comprehensive (loss) income	(9)	6
Ending Balance	0	12
Unrecognized (Losses) Gains and Prior Service Cost, Net [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(646)	(554)
Other comprehensive (loss) income before reclassifications, net of tax	0	0
Amounts reclassified from AOCI, net of tax	39	27
Net current period other comprehensive (loss) income	39	27
Ending Balance	$ (607)	$ (527)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive (Loss) Income (AOCI), Summary of Amounts Reclassified from AOCI into Net Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations before income taxes	$ 226	$ 192	$ 679	$ 645
Provision for income taxes	(18)	(46)	(90)	(147)
Income from continuing operations	208	146	589	498
Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations	(15)	(7)	(41)	(25)
Unrealized Gains (Losses) on Hedging Instruments [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations before income taxes	(3)	2	(2)	3
Provision for income taxes	0	(1)	0	(1)
Income from continuing operations	(3)	1	(2)	2
Amortization of Defined Benefit Pension and Postretirement Items [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net loss	(16)	(13)	(51)	(43)
Provision for income taxes	4	5	12	16
Income from continuing operations	(12)	(8)	(39)	(27)
Product [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of Goods and services sold	1,324	1,189	3,864	3,630
Product [Member] | Unrealized Gains (Losses) on Hedging Instruments [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of Goods and services sold	$ (3)	$ 2	$ (2)	$ 3

Equity (Details)

Equity (Details) - USD ($)	Oct. 22, 2018	Jul. 10, 2018	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017	May 08, 2017
Class of Stock [Line Items]
Aggregate amount of repurchased shares					$ 322,000,000	$ 91,000,000
Cash dividends declared per common share (in dollars per share)		$ 0.80	$ 0.8	$ 0.75	$ 2.40	$ 2.25
Dividend declared date					Jul. 10, 2018
Dividend paid date					Sep. 17, 2018
Dividend paid, record date					Aug. 17, 2018
Cash dividends					$ 191,000,000
Accrued dividends through payment					2,000,000
Subsequent Event [Member]
Class of Stock [Line Items]
Cash dividends declared per common share (in dollars per share)	$ 0.80
Treasury Stock [Member]
Class of Stock [Line Items]
Aggregate amount of repurchased shares					$ 322,000,000	$ 91,000,000
Share Repurchase Program May 8, 2017 [Member]
Class of Stock [Line Items]
Amount of shares authorized to be repurchased							$ 1,500,000,000
Share Repurchase Program December 4, 2014 [Member] | Treasury Stock [Member]
Class of Stock [Line Items]
Number of common shares repurchased (in shares)					1,637,299
Average price per share of repurchased shares (in dollars per share)					$ 196.64

L3's Earnings Per Common Shar_2

L3's Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Reconciliation of Net Income [Abstract]
Net income	$ 208	$ 25	$ 795	$ 400
Net income from continuing operations attributable to noncontrolling interests	(6)	(3)	(15)	(12)
Net income attributable to L3	202	22	780	388
Earnings (loss) attributable to L3' s common shareholders [Abstract]
Continuing operations	202	143	574	486
Discontinued operations, net of income tax	0	(121)	206	(98)
Net income attributable to L3	$ 202	$ 22	$ 780	$ 388
Basic [Abstract]
Weighted average common shares outstanding (in shares)	78.5	78.2	78.4	78
Basic earnings (loss) per share [Abstract]
Continuing operations (in dollars per share)	$ 2.57	$ 1.83	$ 7.32	$ 6.23
Discontinued operations (in dollars per share)	0	(1.55)	2.63	(1.26)
Basic earnings per share (in dollars per share)	$ 2.57	$ 0.28	$ 9.95	$ 4.97
Common and potential common shares [Abstract]
Weighted average common shares outstanding (in shares)	78.5	78.2	78.4	78
Effect of dilutive securities (in shares)	0.9	1.6	1.2	1.6
Common and potential common shares (in shares)	79.4	79.8	79.6	79.6
Diluted earnings (loss) per share [Abstract]
Continuing operations (in dollars per share)	$ 2.54	$ 1.79	$ 7.21	$ 6.10
Discontinued operations, net of income tax (in dollars per share)	0	(1.51)	2.59	(1.23)
Diluted earnings per share (in dollars per share)	$ 2.54	$ 0.28	$ 9.80	$ 4.87
Shares excluded from computation of diluted earnings per share (in shares)	0.3	0.4	0.3	0.3

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2018	Sep. 28, 2018	Feb. 16, 2018	Dec. 31, 2017
Liabilities [Abstract]
Contingent consideration	$ 31	$ 16		$ 31
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	31
Acquisitions and investments	10
Cash payments	(7)
Changes in fair value of contingent consideration, net	(18)
Balance at end of period	16
Recurring [Member] | Level 1 [Member]
Assets [Abstract]
Cash equivalents		167		310
Derivatives (foreign currency forward contracts)		0		0
Total assets		167		310
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
Recurring [Member] | Level 2 [Member]
Assets [Abstract]
Cash equivalents		0		0
Derivatives (foreign currency forward contracts)		4		11
Total assets		4		11
Liabilities [Abstract]
Derivatives (foreign currency forward contracts)		6		1
Contingent consideration	0	0		0
Total liabilities		6		1
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	0
Balance at end of period	0
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	31	16		31
Total liabilities		16		$ 31
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	31
Balance at end of period	16
Peak Nano [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Liabilities [Abstract]
Contingent consideration	0	$ 0	$ 6
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at end of period	$ 0

Financial Instruments (Details)

Financial Instruments (Details) - USD ($) $ in Millions	Sep. 28, 2018	Dec. 31, 2017
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes	$ 3,320	$ 3,330
Foreign currency forward contracts	(2)	10
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes	3,338	3,502
Foreign currency forward contracts	$ (2)	$ 10

Derivative Financial Instrume_3

Derivative Financial Instruments, Outstanding Forward Contracts by Currency (Details) - Foreign Currency Forward Contracts [Member] $ in Millions	Sep. 28, 2018USD ($)
Derivative [Line Items]
Notional amounts	$ 419
Canadian Dollar [Member]
Derivative [Line Items]
Notional amounts	155
U.S. Dollar [Member]
Derivative [Line Items]
Notional amounts	141
Euro [Member]
Derivative [Line Items]
Notional amounts	97
United Arab Emirates Dirham [Member]
Derivative [Line Items]
Notional amounts	12
British Pound [Member]
Derivative [Line Items]
Notional amounts	10
New Zealand Dollar
Derivative [Line Items]
Notional amounts	$ 4

Derivative Financial Instrume_4

Derivative Financial Instruments, Fair Value on Consolidated Balance Sheet (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Pre-tax loss on foreign currency forward contracts	$ (3)		$ (2)
Pre-tax gain on foreign currency forward contracts		$ 2		$ 3
Estimated net amount of existing gains expected to be reclassified into income within the next 12 months	3		3
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	3		3		$ 11
Other Current Assets [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	3		3		11
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	1		1		0
Other Assets [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	1		1		0
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	5		5		1
Other Current Liabilities [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	5		5		1
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	1		1		0
Other Liabilities [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	$ 1		$ 1		$ 0

Commitments and Contingencies (

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

Pension and Other Postretirem_3

Pension and Other Postretirement Benefits, Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Pension Plans [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 25	$ 22	$ 77	$ 72
Interest cost	36	35	108	106
Expected return on plan assets	(56)	(48)	(168)	(146)
Amortization of prior service costs (credits)	(1)	1	(1)	1
Amortization of net loss (gains)	18	14	55	45
Curtailment losses	0	2	0	2
Net periodic benefit cost	22	26	71	80
Postretirement Benefit Plans [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	1	1	2
Interest cost	2	2	4	4
Expected return on plan assets	(2)	(1)	(4)	(3)
Amortization of prior service costs (credits)	(1)	(1)	(1)	(1)
Amortization of net loss (gains)	0	(1)	(2)	(2)
Curtailment losses	0	0	0	0
Net periodic benefit cost	$ (1)	0	$ (2)	$ 0
ISRS [Member] | Pension Plans [Member]
Components of net periodic benefit cost [Abstract]
Curtailment losses		$ 2

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits, Contributions (Details) $ in Millions	9 Months Ended
	Sep. 28, 2018USD ($)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit plans	$ 94
Expected contributions to plans during the remainder of fiscal year	6
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit plans	$ 4

Stock-Based Compensation, Stock

Stock-Based Compensation, Stock Options (Details) - Stock Options [Member]	9 Months Ended
	Sep. 28, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares) | shares	221,886
Weighted average exercise price (in dollars per share)	$ 208.92
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)	$ 37.72
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected holding period	5 years 2 months 12 days
Expected volatility	19.80%
Expected dividend yield	1.80%
Risk-free interest rate	2.70%

Stock-Based Compensation, Restr

Stock-Based Compensation, Restricted Stock Units (Details) - Unvested Restricted Stock Awards [Member]	9 Months Ended
	Sep. 28, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in shares) | shares	250,105
Weighted average grant date fair value (in dollars per share) | $ / shares	$ 210.12
Vesting period	3 years
Retirement eligibility, employee age	60 years
Service period, minimum	5 years
Retirement eligibility, employee age requirement, without minimum service period	65 years
Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year

Stock-Based Compensation, Perfo

Stock-Based Compensation, Performance Units (Details) - Performance Unit Awards [Member] - $ / shares	3 Months Ended	9 Months Ended
	Sep. 29, 2017	Sep. 28, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in shares)	22,325
Weighted average grant date fair value (in dollars per share)		$ 209.91
Length of service after grant date		3 years
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range		0.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout range		200.00%

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Supplemental Cash Flow Elements [Abstract]
Interest paid	$ 125	$ 120
Income tax payments	93	129
Income tax refunds	$ 4	$ 14

Segment Information and Disag_3

Segment Information and Disaggregation of Net Sales (Details) $ in Millions	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 28, 2018USD ($)Segment	Sep. 29, 2017USD ($)	Jun. 29, 2018Segment	Sep. 28, 2018USD ($)Segment	Sep. 29, 2017USD ($)	Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	3		4	3
Net Sales [Abstract]
Net sales	$ 2,519	$ 2,293		$ 7,473	$ 6,999
Operating Income [Abstract]
(Loss) gain on the sale of the Crestview & TCS Businesses	(4)	0		44	0
Merger, acquisition and divestiture related expenses	(5)	0		(5)	0
Operating income	272	232		844	763
Depreciation and amortization [Abstract]
Depreciation and amortization	54	55		170	161
Total Assets:
Assets held for sale	0			0		$ 138	$ 135
Assets of discontinued operations	0			0		285	306
Total assets	13,184			13,184		$ 12,730	12,729
ISRS [Member]
Net Sales [Abstract]
Net sales	1,096			3,221
C&NS [Member]
Net Sales [Abstract]
Net sales	734			2,243
Electronic Systems [Member]
Net Sales [Abstract]
Net sales	689			2,009
Operating Segments [Member]
Operating Income [Abstract]
Operating income	281	232		805	763
Operating Segments [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	1,099	968		3,250	2,940
Operating Income [Abstract]
Operating income	121	73		321	256
Depreciation and amortization [Abstract]
Depreciation and amortization	20	21		64	63
Total Assets:
Total assets	4,813			4,813			4,164
Operating Segments [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	745	759		2,270	2,290
Operating Income [Abstract]
Operating income	69	81		208	277
Depreciation and amortization [Abstract]
Depreciation and amortization	15	17		48	49
Total Assets:
Total assets	3,722			3,722			3,476
Operating Segments [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	703	584		2,047	1,839
Operating Income [Abstract]
Operating income	91	78		276	230
Depreciation and amortization [Abstract]
Depreciation and amortization	19	17		58	49
Total Assets:
Total assets	4,159			4,159			3,939
Corporate [Member]
Total Assets:
Total assets	490			490			$ 709
Elimination of Intercompany Sales [Member]
Net Sales [Abstract]
Net sales	(28)	$ (18)		(94)	$ (70)
Department of Defense [Member]
Net Sales [Abstract]
Net sales	1,579			4,874
Department of Defense [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	709			2,227
Department of Defense [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	561			1,679
Department of Defense [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	309			968
Other U.S. Government [Member]
Net Sales [Abstract]
Net sales	124			310
Other U.S. Government [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	48			108
Other U.S. Government [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	21			74
Other U.S. Government [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	55			128
Total U. S. Government [Member]
Net Sales [Abstract]
Net sales	1,703			5,184
Total U. S. Government [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	757			2,335
Total U. S. Government [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	582			1,753
Total U. S. Government [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	364			1,096
Foreign Government Debt [Member]
Net Sales [Abstract]
Net sales	412			1,115
Foreign Government Debt [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	293			733
Foreign Government Debt [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	71			242
Foreign Government Debt [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	48			140
Commercial - Foreign [Member]
Net Sales [Abstract]
Net sales	203			641
Commercial - Foreign [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	8			51
Commercial - Foreign [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	25			87
Commercial - Foreign [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	170			503
Commercial - Domestic [Member]
Net Sales [Abstract]
Net sales	201			533
Commercial - Domestic [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	38			102
Commercial - Domestic [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	56			161
Commercial - Domestic [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	$ 107			$ 270

Segment Information and Disag_4

Segment Information and Disaggregation of Net Sales - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Disaggregation of Revenue [Line Items]
Direct sales to end customer as percent of consolidated sales (percent)	65.00%		64.00%
Indirect sales as subcontractor or supplier as percent of consolidated sales (percent)	35.00%		36.00%
Fixed price incentive fee type contracts as percent of net sales (percent)	1.00%
Cost-plus and incentive fee type contracts as percent of net sales (percent)	2.00%		3.00%
Total sales	$ 2,519	$ 2,293	$ 7,473	$ 6,999
ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,096		3,221
C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	734		2,243
Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	689		2,009
Department of Defense [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,579		4,874
Department of Defense [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	709		2,227
Department of Defense [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	561		1,679
Department of Defense [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	309		968
Other U.S. Government [Member]
Disaggregation of Revenue [Line Items]
Total sales	124		310
Other U.S. Government [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	48		108
Other U.S. Government [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	21		74
Other U.S. Government [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	55		128
Total U. S. Government [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,703		5,184
Total U. S. Government [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	757		2,335
Total U. S. Government [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	582		1,753
Total U. S. Government [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	364		1,096
Foreign Government Debt [Member]
Disaggregation of Revenue [Line Items]
Total sales	412		1,115
Foreign Government Debt [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	293		733
Foreign Government Debt [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	71		242
Foreign Government Debt [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	48		140
Commercial - Foreign [Member]
Disaggregation of Revenue [Line Items]
Total sales	203		641
Commercial - Foreign [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	8		51
Commercial - Foreign [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	25		87
Commercial - Foreign [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	170		503
Commercial - Domestic [Member]
Disaggregation of Revenue [Line Items]
Total sales	201		533
Commercial - Domestic [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	38		102
Commercial - Domestic [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	56		161
Commercial - Domestic [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	107		270
Product [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,736	1,584	5,168	4,868
Product [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	712		2,085
Product [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	543		1,668
Product [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	481		1,415
Services [Member]
Disaggregation of Revenue [Line Items]
Total sales	783	$ 709	2,305	$ 2,131
Services [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	384		1,136
Services [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	191		575
Services [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	208		594
Fixed-price Contract [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,822		5,387
Fixed-price Contract [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	697		2,046
Fixed-price Contract [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	519		1,626
Fixed-price Contract [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	606		1,715
Cost-plus Contract [Member]
Disaggregation of Revenue [Line Items]
Total sales	632		1,853
Cost-plus Contract [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	362		1,031
Cost-plus Contract [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	195		552
Cost-plus Contract [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	75		270
Time-and-materials Contract [Member]
Disaggregation of Revenue [Line Items]
Total sales	65		233
Time-and-materials Contract [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	37		144
Time-and-materials Contract [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	20		65
Time-and-materials Contract [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	8		24
Cost to Cost Method [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,865		5,609
Cost to Cost Method [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	813		2,456
Cost to Cost Method [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	678		1,932
Cost to Cost Method [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	374		1,221
Point in Time [Member]
Disaggregation of Revenue [Line Items]
Total sales	431		1,347
Point in Time [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	220		604
Point in Time [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	38		238
Point in Time [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	173		505
Output Method [Member]
Disaggregation of Revenue [Line Items]
Total sales	152		314
Output Method [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	18		47
Output Method [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	4		17
Output Method [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	130		250
Billing Method [Member]
Disaggregation of Revenue [Line Items]
Total sales	71		203
Billing Method [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	45		114
Billing Method [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	14		56
Billing Method [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	$ 12		$ 33

Severance and Restructuring R_3

Severance and Restructuring Related Costs (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 28, 2018USD ($)	Sep. 29, 2017USD ($)	Sep. 28, 2018USD ($)Employees	Sep. 29, 2017USD ($)	Dec. 31, 2017USD ($)Employees
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs			$ 18		$ 101
Number of employees of restructuring costs | Employees			500		1,500
Remaining balance of employee severance and restructuring costs	$ 13		$ 13		$ 23
ISRS [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	2	$ 15	4	$ 17
C&NS [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	0	17	9	36
Electronic Systems [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	2	2	5	7
Consolidated [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	4	34	18	60
Pension Plans [Member]
Restructuring Cost and Reserve [Line Items]
Curtailment losses	$ 0	2	$ 0	$ 2
Pension Plans [Member] | ISRS [Member]
Restructuring Cost and Reserve [Line Items]
Curtailment losses		$ 2

Severance and Restructuring R_4

Severance and Restructuring Related Costs - Restructuring Reserve (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 28, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Balance at beginning of period	$ 23
Additional provisions	18	$ 101
Cash payments	(28)
Balance at end of period	$ 13	$ 23

Subsequent Event (Details)

Subsequent Event (Details) - Subsequent Event [Member]	Oct. 14, 2018
Subsequent Event [Line Items]
Ownership percentage after merger (percent)	46.00%
Harris Corporation [Member]
Subsequent Event [Line Items]
Ratio of Harris shares received for every L3 common share	1.30
Harris Corporation [Member]
Subsequent Event [Line Items]
Ownership percentage after merger (percent)	54.00%

Condensed Combining Financial_3

Condensed Combining Financial Information of L3 and Its Subsidiaries- Condensed Combining Balance Sheets (Details) - USD ($) $ in Millions	Sep. 28, 2018	Jan. 01, 2018	Dec. 31, 2017	Sep. 29, 2017	Dec. 31, 2016
Current assets [Abstract]
Cash and cash equivalents	$ 507		$ 662	$ 439	$ 363
Billed receivables, net	900		723
Contracts in process	0	$ 0	1,933
Contract assets	1,707	1,349	0
Inventories	911	926	389
Prepaid expenses and other current assets	410		689
Assets held for sale	0		135
Assets of discontinued operations	0	285	306
Total current assets	4,435	4,400	4,448
Goodwill	6,834		6,615
Other assets	1,915		1,666
Investment in and amounts due from consolidated subsidiaries	0		0
Total assets	13,184	12,730	12,729
Current liabilities	2,260		2,136
Liabilities held for sale	0	16	17
Liabilities of discontinued operations	0	203	226
Amounts due to consolidated subsidiaries	0		0
Other long-term liabilities	1,893		1,869
Long-term debt	3,320		3,330
Total liabilities	7,473	7,566	7,578
L3 shareholders' equity	5,642		5,083
Noncontrolling interests	69		68
Total equity	5,711	$ 5,164	5,151	5,069	4,624
Total liabilities and equity	13,184		12,729
Eliminations [Member]
Current assets [Abstract]
Cash and cash equivalents	(23)		(71)	(18)	(107)
Billed receivables, net	0		0
Contracts in process			0
Contract assets	0
Inventories	0
Prepaid expenses and other current assets	0		0
Assets held for sale			0
Assets of discontinued operations			0
Total current assets	(23)		(71)
Goodwill	0		0
Other assets	0		0
Investment in and amounts due from consolidated subsidiaries	(12,839)		(11,972)
Total assets	(12,862)		(12,043)
Current liabilities	(23)		(71)
Liabilities held for sale			0
Liabilities of discontinued operations			0
Amounts due to consolidated subsidiaries	(444)		(391)
Other long-term liabilities	0		0
Long-term debt	0		0
Total liabilities	(467)		(462)
L3 shareholders' equity	(12,464)		(11,649)
Noncontrolling interests	69		68
Total equity	(12,395)		(11,581)
Total liabilities and equity	(12,862)		(12,043)
L-3 [Member]
Current assets [Abstract]
Cash and cash equivalents	258		432	193	262
Billed receivables, net	302		266
Contracts in process			706
Contract assets	612
Inventories	382
Prepaid expenses and other current assets	133		330
Assets held for sale			0
Assets of discontinued operations			306
Total current assets	1,687		2,040
Goodwill	2,124		2,099
Other assets	695		658
Investment in and amounts due from consolidated subsidiaries	6,144		5,662
Total assets	10,650		10,459
Current liabilities	751		811
Liabilities held for sale			0
Liabilities of discontinued operations			226
Amounts due to consolidated subsidiaries	0		0
Other long-term liabilities	937		1,009
Long-term debt	3,320		3,330
Total liabilities	5,008		5,376
L3 shareholders' equity	5,642		5,083
Noncontrolling interests	0		0
Total equity	5,642		5,083
Total liabilities and equity	10,650		10,459
Guarantor Subsidiaries [Member]
Current assets [Abstract]
Cash and cash equivalents	21		16	13	5
Billed receivables, net	322		244
Contracts in process			912
Contract assets	878
Inventories	294
Prepaid expenses and other current assets	199		235
Assets held for sale			135
Assets of discontinued operations			0
Total current assets	1,714		1,542
Goodwill	3,011		2,932
Other assets	767		687
Investment in and amounts due from consolidated subsidiaries	6,695		6,310
Total assets	12,187		11,471
Current liabilities	900		832
Liabilities held for sale			17
Liabilities of discontinued operations			0
Amounts due to consolidated subsidiaries	0		0
Other long-term liabilities	791		729
Long-term debt	0		0
Total liabilities	1,691		1,578
L3 shareholders' equity	10,496		9,893
Noncontrolling interests	0		0
Total equity	10,496		9,893
Total liabilities and equity	12,187		11,471
Non-Guarantor Subsidiaries [Member]
Current assets [Abstract]
Cash and cash equivalents	251		285	$ 251	$ 203
Billed receivables, net	276		213
Contracts in process			315
Contract assets	217
Inventories	235
Prepaid expenses and other current assets	78		124
Assets held for sale			0
Assets of discontinued operations			0
Total current assets	1,057		937
Goodwill	1,699		1,584
Other assets	453		321
Investment in and amounts due from consolidated subsidiaries	0		0
Total assets	3,209		2,842
Current liabilities	632		564
Liabilities held for sale			0
Liabilities of discontinued operations			0
Amounts due to consolidated subsidiaries	444		391
Other long-term liabilities	165		131
Long-term debt	0		0
Total liabilities	1,241		1,086
L3 shareholders' equity	1,968		1,756
Noncontrolling interests	0		0
Total equity	1,968		1,756
Total liabilities and equity	$ 3,209		$ 2,842

Condensed Combining Financial_4

Condensed Combining Financial Information of L3 and Its Subsidiaries- Condensed Combining Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Condensed Financial Statements, Captions [Line Items]
Total sales	$ 2,519	$ 2,293	$ 7,473	$ 6,999
Total operating costs and expenses	(2,238)	(2,061)	(6,668)	(6,236)
Loss on sale of the Crestview Aerospace and TCS businesses	(4)	0	44	0
Merger, acquisition and divestiture related expenses	(5)	0	(5)	0
Operating income	272	232	844	763
Interest expense	(40)	(42)	(125)	(126)
Interest and other income, net	15	2	29	8
Debt retirement charge	(21)	0	(69)	0
Income from continuing operations before income taxes	226	192	679	645
Provision (benefit) for income taxes	(18)	(46)	(90)	(147)
Equity in net loss of consolidated subsidiaries	0	0	0	0
Income from continuing operations	208	146	589	498
Loss from discontinued operations, net of income taxes	0	(121)	206	(98)
Net income	208	25	795	400
Net income attributable to noncontrolling interests	(6)	(3)	(15)	(12)
Net income attributable to L3	202	22	780	388
Comprehensive income attributable to L3	213	85	768	541
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	(83)	(86)	(275)	(263)
Total operating costs and expenses	83	86	275	263
Loss on sale of the Crestview Aerospace and TCS businesses	0		0
Merger, acquisition and divestiture related expenses	0		0
Operating income	0	0	0	0
Interest expense	0	0	0	0
Interest and other income, net	0	0	0	0
Debt retirement charge	0		0
Income from continuing operations before income taxes	0	0	0	0
Provision (benefit) for income taxes	0	0	0	0
Equity in net loss of consolidated subsidiaries	(195)	(139)	(606)	(475)
Income from continuing operations		(139)	(606)	(475)
Loss from discontinued operations, net of income taxes		0	0	0
Net income	(195)	(139)	(606)	(475)
Net income attributable to noncontrolling interests	(6)	(3)	(15)	(12)
Net income attributable to L3	(201)	(142)	(621)	(487)
Comprehensive income attributable to L3	(198)	(240)	(533)	(718)
L-3 [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	872	836	2,598	2,580
Total operating costs and expenses	(759)	(747)	(2,300)	(2,328)
Loss on sale of the Crestview Aerospace and TCS businesses	0		0
Merger, acquisition and divestiture related expenses	(5)		(5)
Operating income	108	89	293	252
Interest expense	(40)	(41)	(124)	(125)
Interest and other income, net	14	1	25	6
Debt retirement charge	(21)		(69)
Income from continuing operations before income taxes	61	49	125	133
Provision (benefit) for income taxes	(6)	(11)	(16)	(30)
Equity in net loss of consolidated subsidiaries	147	105	465	383
Income from continuing operations		143	574	486
Loss from discontinued operations, net of income taxes		(121)	206	(98)
Net income	202	22	780	388
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to L3	202	22	780	388
Comprehensive income attributable to L3	213	85	768	541
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	1,274	1,157	3,841	3,546
Total operating costs and expenses	(1,200)	(1,081)	(3,594)	(3,226)
Loss on sale of the Crestview Aerospace and TCS businesses	(4)		44
Merger, acquisition and divestiture related expenses	0		0
Operating income	70	76	291	320
Interest expense	0	0	0	0
Interest and other income, net	1	0	2	0
Debt retirement charge	0		0
Income from continuing operations before income taxes	71	76	293	320
Provision (benefit) for income taxes	(4)	(19)	(39)	(73)
Equity in net loss of consolidated subsidiaries	48	34	141	92
Income from continuing operations		91	395	339
Loss from discontinued operations, net of income taxes		0	0	0
Net income	115	91	395	339
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to L3	115	91	395	339
Comprehensive income attributable to L3	115	139	353	447
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	456	386	1,309	1,136
Total operating costs and expenses	(362)	(319)	(1,049)	(945)
Loss on sale of the Crestview Aerospace and TCS businesses	0		0
Merger, acquisition and divestiture related expenses	0		0
Operating income	94	67	260	191
Interest expense	0	(1)	(1)	(1)
Interest and other income, net	0	1	2	2
Debt retirement charge	0		0
Income from continuing operations before income taxes	94	67	261	192
Provision (benefit) for income taxes	(8)	(16)	(35)	(44)
Equity in net loss of consolidated subsidiaries	0	0	0	0
Income from continuing operations		51	226	148
Loss from discontinued operations, net of income taxes		0	0	0
Net income	86	51	226	148
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to L3	86	51	226	148
Comprehensive income attributable to L3	$ 83	$ 101	$ 180	$ 271

Condensed Combining Financial_5

Condensed Combining Financial Information of L3 and Its Subsidiaries- Condensed Combining Statements of Cash Flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Operating activities [Abstract]
Net cash from operating activities from continuing operations	$ 342	$ 581
Investing activities [Abstract]
Business acquisitions, net of cash acquired	(368)	(291)
Proceeds from sale of businesses, net of closing date cash balances	535	18
Other investing activities	(193)	(91)
Net cash used in investing activities from continuing operations	(26)	(364)
Financing activities [Abstract]
Proceeds from sale of senior notes	1,798	0
Repurchases and redemptions of senior notes	(1,865)	0
Common stock repurchased	(322)	(91)
Dividends paid on L3's common stock	(191)	(178)
Other financing activities	111	30
Net cash used in financing activities from continuing operations	(469)	(239)
Effect of foreign currency exchange rate changes on cash	(9)	16
Net decrease in cash and cash equivalents of discontinued operations	7	82
Net (decrease) increase in cash	(155)	76
Cash and cash equivalents, beginning of the period	662	363
Cash and cash equivalents, end of the period	507	439
Eliminations [Member]
Operating activities [Abstract]
Net cash from operating activities from continuing operations	(7)	(41)
Investing activities [Abstract]
Business acquisitions, net of cash acquired	0	0
Proceeds from sale of businesses, net of closing date cash balances	0	0
Other investing activities	0	0
Net cash used in investing activities from continuing operations	0	0
Financing activities [Abstract]
Proceeds from sale of senior notes	0
Repurchases and redemptions of senior notes	0
Common stock repurchased	0	0
Dividends paid on L3's common stock	0	0
Other financing activities	55	130
Net cash used in financing activities from continuing operations	55	130
Effect of foreign currency exchange rate changes on cash	0	0
Net decrease in cash and cash equivalents of discontinued operations	0	0
Net (decrease) increase in cash	48	89
Cash and cash equivalents, beginning of the period	(71)	(107)
Cash and cash equivalents, end of the period	(23)	(18)
L-3 [Member]
Operating activities [Abstract]
Net cash from operating activities from continuing operations	248	248
Investing activities [Abstract]
Business acquisitions, net of cash acquired	(192)	(291)
Proceeds from sale of businesses, net of closing date cash balances	360	17
Other investing activities	(99)	(67)
Net cash used in investing activities from continuing operations	69	(341)
Financing activities [Abstract]
Proceeds from sale of senior notes	1,798
Repurchases and redemptions of senior notes	(1,865)
Common stock repurchased	(322)	(91)
Dividends paid on L3's common stock	(191)	(178)
Other financing activities	82	211
Net cash used in financing activities from continuing operations	(498)	(58)
Effect of foreign currency exchange rate changes on cash	0	0
Net decrease in cash and cash equivalents of discontinued operations	7	82
Net (decrease) increase in cash	(174)	(69)
Cash and cash equivalents, beginning of the period	432	262
Cash and cash equivalents, end of the period	258	193
Guarantor Subsidiaries [Member]
Operating activities [Abstract]
Net cash from operating activities from continuing operations	(30)	187
Investing activities [Abstract]
Business acquisitions, net of cash acquired	0	0
Proceeds from sale of businesses, net of closing date cash balances	175	0
Other investing activities	(59)	(5)
Net cash used in investing activities from continuing operations	116	(5)
Financing activities [Abstract]
Proceeds from sale of senior notes	0
Repurchases and redemptions of senior notes	0
Common stock repurchased	0	0
Dividends paid on L3's common stock	0	0
Other financing activities	(81)	(174)
Net cash used in financing activities from continuing operations	(81)	(174)
Effect of foreign currency exchange rate changes on cash	0	0
Net decrease in cash and cash equivalents of discontinued operations	0	0
Net (decrease) increase in cash	5	8
Cash and cash equivalents, beginning of the period	16	5
Cash and cash equivalents, end of the period	21	13
Non-Guarantor Subsidiaries [Member]
Operating activities [Abstract]
Net cash from operating activities from continuing operations	131	187
Investing activities [Abstract]
Business acquisitions, net of cash acquired	(176)	0
Proceeds from sale of businesses, net of closing date cash balances	0	1
Other investing activities	(35)	(19)
Net cash used in investing activities from continuing operations	(211)	(18)
Financing activities [Abstract]
Proceeds from sale of senior notes	0
Repurchases and redemptions of senior notes	0
Common stock repurchased	0	0
Dividends paid on L3's common stock	0	0
Other financing activities	55	(137)
Net cash used in financing activities from continuing operations	55	(137)
Effect of foreign currency exchange rate changes on cash	(9)	16
Net decrease in cash and cash equivalents of discontinued operations	0	0
Net (decrease) increase in cash	(34)	48
Cash and cash equivalents, beginning of the period	285	203
Cash and cash equivalents, end of the period	$ 251	$ 251

Condensed Combining Financial_6

Condensed Combining Financial Information of L3 and Its Subsidiaries - Financial Statement Revisions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Condensed Financial Statements, Captions [Line Items]
Total sales	$ 2,519	$ 2,293	$ 7,473	$ 6,999
Total operating costs and expenses	(2,238)	(2,061)	(6,668)	(6,236)
Operating income (loss)	272	232	844	763
Interest expense	(40)	(42)	(125)	(126)
Interest and other income, net	15	2	29	8
Income (loss) from continuing operations before income taxes	226	192	679	645
Provision (benefit) for income taxes	(18)	(46)	(90)	(147)
Equity in net (loss) income of consolidated subsidiaries	0	0	0	0
Income (loss) from continuing operations	208	146	589	498
Loss from discontinued operations, net of income taxes	0	(121)	206	(98)
Net income	208	25	795	400
Net income attributable to noncontrolling interests	(6)	(3)	(15)	(12)
Net income (loss) attributable to L3	202	22	780	388
Comprehensive income (loss) attributable to L3	213	85	768	541
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	(83)	(86)	(275)	(263)
Total operating costs and expenses	83	86	275	263
Goodwill impairment charge		0		0
Operating income (loss)	0	0	0	0
Interest expense	0	0	0	0
Interest and other income, net	0	0	0	0
Income (loss) from continuing operations before income taxes	0	0	0	0
Provision (benefit) for income taxes	0	0	0	0
Equity in net (loss) income of consolidated subsidiaries	(195)	(139)	(606)	(475)
Income (loss) from continuing operations		(139)	(606)	(475)
Loss from discontinued operations, net of income taxes		0	0	0
Net income	(195)	(139)	(606)	(475)
Net income attributable to noncontrolling interests	(6)	(3)	(15)	(12)
Net income (loss) attributable to L3	(201)	(142)	(621)	(487)
Comprehensive income (loss) attributable to L3	(198)	(240)	(533)	(718)
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	872	836	2,598	2,580
Total operating costs and expenses	(759)	(747)	(2,300)	(2,328)
Goodwill impairment charge		0		0
Operating income (loss)	108	89	293	252
Interest expense	(40)	(41)	(124)	(125)
Interest and other income, net	14	1	25	6
Income (loss) from continuing operations before income taxes	61	49	125	133
Provision (benefit) for income taxes	(6)	(11)	(16)	(30)
Equity in net (loss) income of consolidated subsidiaries	147	105	465	383
Income (loss) from continuing operations		143	574	486
Loss from discontinued operations, net of income taxes		(121)	206	(98)
Net income	202	22	780	388
Net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to L3	202	22	780	388
Comprehensive income (loss) attributable to L3	213	85	768	541
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	1,274	1,157	3,841	3,546
Total operating costs and expenses	(1,200)	(1,081)	(3,594)	(3,226)
Goodwill impairment charge		0		0
Operating income (loss)	70	76	291	320
Interest expense	0	0	0	0
Interest and other income, net	1	0	2	0
Income (loss) from continuing operations before income taxes	71	76	293	320
Provision (benefit) for income taxes	(4)	(19)	(39)	(73)
Equity in net (loss) income of consolidated subsidiaries	48	34	141	92
Income (loss) from continuing operations		91	395	339
Loss from discontinued operations, net of income taxes		0	0	0
Net income	115	91	395	339
Net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to L3	115	91	395	339
Comprehensive income (loss) attributable to L3	115	139	353	447
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	456	386	1,309	1,136
Total operating costs and expenses	(362)	(319)	(1,049)	(945)
Goodwill impairment charge		0		0
Operating income (loss)	94	67	260	191
Interest expense	0	(1)	(1)	(1)
Interest and other income, net	0	1	2	2
Income (loss) from continuing operations before income taxes	94	67	261	192
Provision (benefit) for income taxes	(8)	(16)	(35)	(44)
Equity in net (loss) income of consolidated subsidiaries	0	0	0	0
Income (loss) from continuing operations		51	226	148
Loss from discontinued operations, net of income taxes		0	0	0
Net income	86	51	226	148
Net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to L3	86	51	226	148
Comprehensive income (loss) attributable to L3	$ 83	101	$ 180	271
Adjustment [Member] | Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales		(3)		(6)
Total operating costs and expenses		3		6
Goodwill impairment charge		0		0
Operating income (loss)		0		0
Interest expense		0		0
Interest and other income, net		0		0
Income (loss) from continuing operations before income taxes		0		0
Provision (benefit) for income taxes		0		0
Equity in net (loss) income of consolidated subsidiaries		(163)		(207)
Income (loss) from continuing operations		(163)		(207)
Loss from discontinued operations, net of income taxes		0		0
Net income		(163)		(207)
Net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to L3		(163)		(207)
Comprehensive income (loss) attributable to L3		(207)		(311)
Adjustment [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales		(4)		(23)
Total operating costs and expenses		(1)		6
Goodwill impairment charge		0		0
Operating income (loss)		(5)		(17)
Interest expense		1		1
Interest and other income, net		(6)		(6)
Income (loss) from continuing operations before income taxes		(10)		(22)
Provision (benefit) for income taxes		1		4
Equity in net (loss) income of consolidated subsidiaries		129		115
Income (loss) from continuing operations		120		97
Loss from discontinued operations, net of income taxes		(120)		(97)
Net income		0		0
Net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to L3		0		0
Comprehensive income (loss) attributable to L3		0		0
Adjustment [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales		(324)		(954)
Total operating costs and expenses		309		920
Goodwill impairment charge		187		187
Operating income (loss)		172		153
Interest expense		0		1
Interest and other income, net		0		0
Income (loss) from continuing operations before income taxes		172		154
Provision (benefit) for income taxes		(43)		(36)
Equity in net (loss) income of consolidated subsidiaries		34		92
Income (loss) from continuing operations		163		210
Loss from discontinued operations, net of income taxes		0		0
Net income		163		210
Net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to L3		163		210
Comprehensive income (loss) attributable to L3		206		313
Adjustment [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales		(22)		(65)
Total operating costs and expenses		24		64
Goodwill impairment charge		0		0
Operating income (loss)		2		(1)
Interest expense		0		0
Interest and other income, net		2		(1)
Income (loss) from continuing operations before income taxes		4		(2)
Provision (benefit) for income taxes		(4)		(1)
Equity in net (loss) income of consolidated subsidiaries		0		0
Income (loss) from continuing operations		0		(3)
Loss from discontinued operations, net of income taxes		0		0
Net income		0		(3)
Net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to L3		0		(3)
Comprehensive income (loss) attributable to L3		1		(2)
As Reported [Member] | Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales		(83)		(257)
Total operating costs and expenses		83		257
Goodwill impairment charge		0		0
Operating income (loss)		0		0
Interest expense		0		0
Interest and other income, net		0		0
Income (loss) from continuing operations before income taxes		0		0
Provision (benefit) for income taxes		0		0
Equity in net (loss) income of consolidated subsidiaries		24		(268)
Income (loss) from continuing operations		24		(268)
Loss from discontinued operations, net of income taxes		0		0
Net income		24		(268)
Net income attributable to noncontrolling interests		(3)		(12)
Net income (loss) attributable to L3		21		(280)
Comprehensive income (loss) attributable to L3		(33)		(407)
As Reported [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales		840		2,603
Total operating costs and expenses		(746)		(2,334)
Goodwill impairment charge		0		0
Operating income (loss)		94		269
Interest expense		(42)		(126)
Interest and other income, net		7		12
Income (loss) from continuing operations before income taxes		59		155
Provision (benefit) for income taxes		(12)		(34)
Equity in net (loss) income of consolidated subsidiaries		(24)		268
Income (loss) from continuing operations		23		389
Loss from discontinued operations, net of income taxes		(1)		(1)
Net income		22		388
Net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to L3		22		388
Comprehensive income (loss) attributable to L3		85		541
As Reported [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales		1,481		4,500
Total operating costs and expenses		(1,390)		(4,146)
Goodwill impairment charge		(187)		(187)
Operating income (loss)		(96)		167
Interest expense		0		(1)
Interest and other income, net		0		0
Income (loss) from continuing operations before income taxes		(96)		166
Provision (benefit) for income taxes		24		(37)
Equity in net (loss) income of consolidated subsidiaries		0		0
Income (loss) from continuing operations		(72)		129
Loss from discontinued operations, net of income taxes		0		0
Net income		(72)		129
Net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to L3		(72)		129
Comprehensive income (loss) attributable to L3		(67)		134
As Reported [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales		408		1,201
Total operating costs and expenses		(343)		(1,009)
Goodwill impairment charge		0		0
Operating income (loss)		65		192
Interest expense		(1)		(1)
Interest and other income, net		(1)		3
Income (loss) from continuing operations before income taxes		63		194
Provision (benefit) for income taxes		(12)		(43)
Equity in net (loss) income of consolidated subsidiaries		0		0
Income (loss) from continuing operations		51		151
Loss from discontinued operations, net of income taxes		0		0
Net income		51		151
Net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to L3		51		151
Comprehensive income (loss) attributable to L3		100		273
Understatement
Condensed Financial Statements, Captions [Line Items]
Equity in net income of consolidated subsidiaries and net income of Guarantor Subsidiaries		$ 34		$ 92