L3 10-Q 1 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 29, 2019	Apr. 26, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	L3 TECHNOLOGIES, INC.
Entity Central Index Key	0001039101
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		79,451,167
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 29, 2019
Entity Emerging Growth Company	false
Entity Small Business	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 29, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 1,108	$ 1,066
Billed receivables, net of allowances of $13 in 2019 and $12 in 2018	804	919
Contract assets	1,735	1,590
Inventories	896	879
Prepaid expenses and other current assets	362	356
Total current assets	4,905	4,810
Property, plant and equipment, net	1,178	1,169
Operating lease right-of-use assets	618	0
Goodwill	6,826	6,808
Identifiable intangible assets	378	390
Other assets	358	341
Total assets	14,263	13,518
Current liabilities:
Accounts payable, trade	672	699
Accrued employment costs	411	491
Accrued expenses	219	251
Contract liabilities	711	669
Income taxes payable	55	49
Other current liabilities	364	288
Total current liabilities	2,432	2,447
Pension and postretirement benefits	1,202	1,211
Deferred income taxes	205	196
Other liabilities	415	436
Operating lease liabilities	569	0
Long-term debt	3,322	3,321
Total liabilities	8,145	7,611
Commitments and contingencies (see Note 19)
Shareholders’ equity:
Common stock: $.01 par value; 300,000,000 shares authorized, 79,397,240 shares outstanding at March 29, 2019 and 78,800,714 shares outstanding at December 31, 2018	6,904	6,866
Treasury stock (at cost), 84,999,711 shares at March 29, 2019 and December 31, 2018	(7,726)	(7,726)
Retained earnings	7,574	7,424
Accumulated other comprehensive loss	(701)	(725)
Total shareholders’ equity	6,051	5,839
Noncontrolling interests	67	68
Total equity	6,118	5,907
Total liabilities and equity	$ 14,263	$ 13,518

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 29, 2019	Dec. 31, 2018
Current assets:
Allowances for billed receivables	$ 13	$ 12
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)	79,397,240	78,800,714
Treasury stock at cost (in shares)	84,999,711	84,999,711

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Net sales:
Total sales	$ 2,700	$ 2,371
Operating costs and expenses:
General and administrative expenses	(382)	(397)
Total operating costs and expenses	(2,389)	(2,120)
Merger, acquisition and divestiture related expenses and losses	(18)	0
Operating income	293	251
Interest expense	(37)	(41)
Interest and other income, net	4	6
Income from continuing operations before income taxes	260	216
Provision for income taxes	(37)	(24)
Income from continuing operations	223	192
Income from discontinued operations, net of income taxes	0	16
Net income	223	208
Net income from continuing operations attributable to noncontrolling interests	(6)	(5)
Net income attributable to L3	$ 217	$ 203
Basic earnings per share attributable to common shareholders:
Continuing operations (in dollars per share)	$ 2.74	$ 2.40
Discontinued operations (in dollars per share)	0	0.20
Basic earnings per share (in dollars per share)	2.74	2.60
Diluted earnings per share attributable to common shareholders:
Continuing operations (in dollars per share)	2.71	2.34
Discontinued operations (in dollars per share)	0	0.20
Diluted earnings per share (in dollars per share)	2.71	2.54
Cash dividends declared per common share (in dollars per share)	$ 0.85	$ 0.8
Weighted average common shares outstanding:
Basic (in shares)	79.2	78.2
Diluted (in shares)	80	79.9
Product [Member]
Net sales:
Total sales	$ 1,932	$ 1,646
Operating costs and expenses:
Cost of Goods and services sold	(1,442)	(1,191)
Service [Member]
Net sales:
Total sales	768	725
Operating costs and expenses:
Cost of Goods and services sold	$ (565)	$ (532)

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions		3 Months Ended
		Mar. 29, 2019	Mar. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income		$ 223	$ 208
Other comprehensive income:
Foreign currency translation adjustments		23	33
Unrealized losses on hedging instruments (1)	[1]	(6)
Unrealized losses on hedging instruments (1)	[1]		(1)
Pension and postretirement benefit plans:
Amortization of net loss and prior service cost previously recognized (2)	[2]	7	14
Total other comprehensive income		24	46
Comprehensive income		247	254
Comprehensive income attributable to noncontrolling interests		(6)	(5)
Comprehensive income attributable to L3		241	249
Income tax (expense) on amortization of net loss and prior service cost previously recognized		$ 2	$ 4
[1]	Net of income tax benefits of $2 million for the quarterly period ended March 29, 2019.
[2]	Net of income taxes of $2 million and $4 million for the quarterly periods ended March 29, 2019 and March 30, 2018, respectively.

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) $ in Millions	3 Months Ended
	Mar. 29, 2019USD ($)
Statement of Comprehensive Income [Abstract]
Income tax benefit on unrealized losses on hedging instruments	$ 2
Income tax (expense) on amortization of net loss and prior service cost previously recognized	$ 2

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, 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	208				203		5
Other comprehensive income (loss)	46					46
Distributions to noncontrolling interests	(6)						(6)
Cash dividends declared	(63)				(63)
Shares issued:
Employee savings plans	34		34
Employee savings plans (in shares)		0.2
Exercise of stock options	55		55
Exercise of stock options (in shares)		0.6
Employee stock purchase plan	0
Employee stock purchase plan (in shares)		0.1
Vesting of restricted stock and performance units
Vesting of restricted stock and performance units (in shares)		0.3
Repurchases of common stock to satisfy tax withholding obligations	(23)		(23)
Repurchases of common stock to satisfy tax withholding obligations (in shares)		(0.1)
Stock-based compensation expense	20		20
Treasury stock purchased	(119)			(119)
Treasury stock purchased (in shares)		(0.6)
Other	4		2		2
Ending Balance at Mar. 30, 2018	5,320	$ 1	6,606	(7,523)	6,814	(645)	67
Ending Balance (in shares) at Mar. 30, 2018		78.4
Beginning Balance at Dec. 31, 2018	5,907	$ 1	6,865	(7,726)	7,424	(725)	68
Beginning Balance (in shares) at Dec. 31, 2018		78.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	223				217		6
Other comprehensive income (loss)	24					24
Distributions to noncontrolling interests	(7)						(7)
Cash dividends declared	(67)				(67)
Shares issued:
Employee savings plans	30		30
Employee savings plans (in shares)		0.2
Exercise of stock options	19		19
Exercise of stock options (in shares)		0.1
Employee stock purchase plan	0
Employee stock purchase plan (in shares)		0.1
Vesting of restricted stock and performance units
Vesting of restricted stock and performance units (in shares)		0.3
Repurchases of common stock to satisfy tax withholding obligations	(22)		(22)
Repurchases of common stock to satisfy tax withholding obligations (in shares)		(0.1)
Stock-based compensation expense	12		12
Other	(1)		(1)
Ending Balance at Mar. 29, 2019	$ 6,118	$ 1	$ 6,903	$ (7,726)	$ 7,574	$ (701)	$ 67
Ending Balance (in shares) at Mar. 29, 2019		79.4

UNAUDITED CONDENSED CONSOLIDA_5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	Jul. 10, 2018	Mar. 29, 2019	Mar. 30, 2018
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 0.85	$ 0.85	$ 0.8

UNAUDITED CONDENSED CONSOLIDA_6

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Operating activities:
Net income	$ 223	$ 208
Less: income from discontinued operations, net of tax	0	(16)
Income from continuing operations	223	192
Depreciation of property, plant and equipment	43	43
Amortization of intangibles and other assets	15	13
Deferred income tax provision	8	16
Stock-based employee compensation expense	12	20
Contributions to employee savings plans in common stock	30	32
Amortization of pension and postretirement benefit plans net loss and prior service cost	9	18
Other non-cash items	5	1
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures, and discontinued operations:
Billed receivables	116	(73)
Contract assets	(142)	(145)
Inventories	(20)	(65)
Prepaid expenses and other current assets	(31)	(99)
Accounts payable, trade	(32)	56
Accrued employment costs	(70)	(54)
Accrued expenses	(31)	(6)
Contract liabilities	43	41
Income taxes	14	(11)
All other operating activities	(18)	(14)
Net cash from (used in) operating activities from continuing operations	174	(35)
Investing activities:
Proceeds from the sale of businesses, net of closing date cash balances	1	0
Working capital adjustment on prior divestitures	(20)	0
Capital expenditures	(49)	(56)
Dispositions of property, plant and equipment	3	2
Other investing activities	(9)	(29)
Net cash used in investing activities from continuing operations	(74)	(83)
Financing activities:
Borrowings under revolving credit facility	0	207
Repayments of borrowings under revolving credit facility	0	(207)
Common stock repurchased	0	(119)
Dividends paid	(70)	(65)
Proceeds from exercises of stock options	19	55
Proceeds from employee stock purchase plan	0	8
Repurchases of common stock to satisfy tax withholding obligations	(22)	(23)
Other financing activities	(7)	(2)
Net cash used in financing activities from continuing operations	(80)	(146)
Effect of foreign currency exchange rate changes on cash and cash equivalents	3	6
Net cash from (used in) discontinued operations:
Operating activities	19	(29)
Investing activities	0	(1)
Net cash from (used in) discontinued operations	19	(30)
Net increase (decrease) cash and cash equivalents	42	(288)
Cash and cash equivalents, beginning of the period	1,066	662
Cash and cash equivalents, end of the period	$ 1,108	$ 374

Description of Business

Description of Business	3 Months Ended
	Mar. 29, 2019
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. L3's structure consists of the following three reportable segments: (1) ISR Systems (ISRS), (2) Communications and Networked Systems (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 sectors are Reconnaissance Mission Systems, Tactical Mission Systems, Integrated Land Systems, Space & Sensors, Surveillance & Strike Systems, Intelligence & Mission Systems, Advanced C 2 ISR Systems and Special Programs. 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 sectors are Communications & Microwave Products, Integrated Maritime Systems and Broadband Communications. 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 markets, such as commercial and military aircraft simulation and training, 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 sectors are Commercial Aviation Solutions, Precision Engagement Systems and Defense Training Solutions. Financial information with respect to each of the Company's segments is included in Note 22 to the unaudited condensed consolidated financial statements and Note 22 to the audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018 . On June 29, 2018, the Company completed the sale of its Vertex Aerospace businesses for a sales 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 $42 million ( $19 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 $234 million ( $177 million after income taxes) related to the Vertex Aerospace business. The results of operations of the Vertex Aerospace business are reported as discontinued operations for all periods presented. During the first quarter of 2019, the Company finalized and paid a working capital adjustment of $20 million related to the sale. See Note 4 for additional information. All references to financial data in this Quarterly Report on Form 10-Q are to the Company’s continuing operations, unless specifically noted. Planned Merger with Harris Corporation 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. On April 4, 2019, Harris and L3 shareholders approved all shareholder proposals necessary to complete the merger of equals transaction to create 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.

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 29, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These unaudited condensed consolidated financial statements for the quarterly period ended March 29, 2019 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, 2018 . 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 voting control are accounted for using the equity method. Investments over which the Company does not have significant influence are accounted for using the cost method. For the classification of 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, 2018 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 cost of sales during the reporting period. The most significant of these estimates and assumptions relate to sales, profit and loss recognition for 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 realizable value, pension and post-retirement benefit obligations, stock-based employee compensation expense, income taxes, including the valuations of deferred tax assets, litigation reserves, useful lives and valuation of recorded amounts of long-lived assets, identifiable intangible assets and goodwill. Changes in estimates are reflected in the periods during which they become known. Actual amounts may differ from these estimates and could differ materially. Revenue Recognition 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. 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. The Company also records sales from performance obligations satisfied at a point in time, which are typically for standard goods. See Note 22 for additional information regarding the composition of the Company’s net sales. Revisions or adjustments to estimates of the transaction price, estimated costs at completion and estimated profit or loss of a performance obligation may be 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 in some cases result in liabilities to complete contracts in a loss position. Net sales recognized from the Company's performance obligations partially satisfied in prior periods were $83 million for the quarterly period ended March 29, 2019 and relate to revisions in contract estimates. The aggregate impact of net changes in contract estimates is presented in the table below. First Quarter Ended March 29, March 30, (in millions, except per share data) Operating income $ 66 $ 50 Diluted earnings per share $ 0.63 $ 0.48 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 quarterly period s ended March 29, 2019 and March 30, 2018 . First Quarter Ended March 29, March 30, Over time (cost-to-cost method) 76 % 76 % Point in time 19 % 18 % Output method 3 % 3 % Billing method 2 % 3 % Total 100 % 100 % Remaining Performance Obligations As of March 29, 2019 , the Company had $12.0 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 $6.5 billion during the remainder of 2019 , $3.4 billion in 2020 , $1.1 billion in 2021 and $1.0 billion in the periods thereafter. Leases Effective January 1, 2019, the Company adopted ASU 2016-02 Leases, (ASC 842), using the optional transition method. In accordance with the optional transition method, the Company initially applied the new standard for existing leases as of January 1, 2019. In addition, in accordance with the optional transition method prior period amounts and disclosures are presented under ASC 840. The cumulative effect of applying ASC 842 was an increase of $640 million to the Company's assets and liabilities. In accordance with ASC 842, the Company recognizes lease assets and liabilities on the balance sheet for operating and finance leases under which the Company is a lessee, except for equipment leases and, as permitted by a practical expedient under the standard, leases with a term of 12 months or less. Equipment leases were not material at January 1, 2019 or March 29, 2019 and therefore not recognized on the balance sheet for these periods. The Company recognizes a lease expense on a straight-line basis over the lease term for equipment leases and leases with a term of 12 months or less. The Company classifies operating lease assets as operating lease right-of-use (ROU) assets and operating lease liabilities in other current liabilities for obligations due within 12 months, or operating lease liabilities for obligations due longer than 12 months. Finance lease assets are classified in property, plant and equipment. Finance lease liabilities are classified in other current liabilities or other liabilities depending on when the obligation is due. Lease assets and liabilities are recognized based on the present value of future lease payments. Lease payments primarily include rent and insurance costs (lease components). The Company's leases also include non-lease components such as real estate taxes and common-area maintenance costs. The Company elected the practical expedient to account for lease and non-lease components as a single component. In certain of the Company's leases, the non-lease components are variable and in accordance with the standard are therefore excluded from lease payments to determine the lease asset. The present value of future lease payments is determined using the Company's incremental borrowing rate at lease commencement over the expected lease term. The Company uses its incremental borrowing rate because the Company's leases do not provide an implicit lease rate. The expected lease term represents the number of years the Company expects to lease the property, including options to extend or terminate the lease when it is reasonably certain that the Company will exercise such option. For operating leases, the lease expense is recognized on a straight-line basis over the expected lease term on the statement of operations as an operating cost. For finance leases, the asset is amortized on a straight-line basis over the lease term, and interest on the lease liability is recognized in interest expense. The amortization of lease assets for the Company's finance leases and interest expense were not material for the three months ended March 29, 2019 . Lessor The Company is a lessor for certain arrangements for flight simulators. These leases meet the criteria for operating lease classification. Lease income associated with these leases is not material. 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 $71 million and $75 million for the quarterly period s ended March 29, 2019 and March 30, 2018 , 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.

New Accounting Standards Implem

New Accounting Standards Implemented	3 Months Ended
	Mar. 29, 2019
Accounting Changes and Error Corrections [Abstract]
New Accounting Standards Implemented	New Accounting Standards Implemented In February 2018, the Financial Accounting Standards Board (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 Company adopted ASU 2018-02 as of January 1, 2019 and elected not to reclassify amounts from AOCI for the stranded tax effects of U.S. Tax Reform. The adoption of ASU 2018-02 did not have any impact on the Company’s 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. 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 adopted ASU 2017-12 effective January 1, 2019. The adoption of this standard did not have a material effect on the Company's financial position, results of operations or cash flows. In February 2016, the FASB issued ASC 842 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 adopted the standard as of January 1, 2019. See Note 2 for additional information.

Acquisitions, Divestitures and

Acquisitions, Divestitures and Discontinued Operations	3 Months Ended
	Mar. 29, 2019
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. The final purchase price for the 2018 acquisitions of ASV Global, L.L.C. (ASV Global), C.K. Industrial Engineers Limited (C.K. Industrial Engineers) and Azimuth Security and Linchpin Labs (Azimuth Security and Linchpin Labs) is subject to customary adjustments for final working capital. The final purchase price allocations for ASV Global and C.K. Industrial Engineers, which are expected to be completed in the second quarter of 2019, and Azimuth Security and Linchpin Labs, which is expected to be completed in the third 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 allocations will have a material impact on its results of operations or financial position. See Note 3 to the audited consolidated financial statements for the year ended December 31, 2018 , included in the Company’s Annual Report on Form 10-K, for additional information about the Company’s 2018 business acquisitions. Unaudited Pro Forma Statements of Operations Data The following unaudited pro forma Statement of Operations data presents the combined results of the Company and its business acquisitions completed during the year ended December 31, 2018 , assuming that the business acquisitions completed during 2018 had occurred on January 1, 2017 . The unaudited pro forma Statement of Operations data below includes adjustments for additional amortization expense related to acquired intangible assets and depreciation assuming the 2018 acquisitions had occurred on January 1, 2017 . First Quarter Ended March 30, 2018 (in millions, except per share data) Pro forma net sales $ 2,404 Pro forma income from continuing operations attributable to L3 $ 191 Pro forma net income attributable to L3 $ 207 Pro forma diluted earnings per share from continuing operations $ 2.39 Pro forma diluted earnings per share $ 2.59 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. On March 6, 2019, the Company acquired an additional 10% interest in Peak Nano and warrants to acquire up to an additional 10% interest, in exchange for $20 million and conversion of a $5 million note receivable. 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. Business Divestitures 2019 Divestitures On February 5, 2019, the Company completed the sale of its L3 Mobile-Vision, Inc. business. The L3 Mobile-Vision, Inc. business, which was within the Company's ISRS segment, primarily provided in-car video systems, body-worn cameras and other law enforcement solutions. The sales price for the business was for $1 million , and the estimated loss on sale was $2 million . Mobile-Vision's results of operations were not material for the quarterly period ended March 29, 2019 . 2018 Divestitures As discussed in Note 1 , on June 29, 2018, the Company completed the sale of its Crestview & TCS Businesses . 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. First Quarter Ended March 30, 2018 (in millions) Net sales $ 33 Income from continuing operations before income taxes $ 1 Discontinued Operations Vertex Aerospace. As discussed in Note 1 , on June 29, 2018, the Company completed the sale of its Vertex Aerospace businesses. 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) total L3 consolidated net assets and (2) L3 consolidated total debt. First Quarter Ended March 30, 2018 (in millions) Net sales $ 371 Operating costs and expenses (349 ) Operating income from discontinued operations 22 Interest expense allocated to discontinued operations (1 ) Income from discontinued operations before income taxes 21 Income tax expense (5 ) Income from discontinued operations, net of income taxes $ 16

Contract Assets and Contract Li

Contract Assets and Contract Liabilities	3 Months Ended
	Mar. 29, 2019
Revenue from Contract with Customer [Abstract]
Contract Assets and Contract Liabilities	Contract Assets and Contract Liabilities The table below presents the components of net contract assets. March 29, December 31, (in millions) Contract assets $ 1,735 $ 1,590 Contract liabilities — current (711 ) (669 ) Contract liabilities — non-current (28 ) (31 ) Net contract assets $ 996 $ 890 Contract assets increased from December 31, 2018 to March 29, 2019 by $145 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 Reconnaissance Mission Systems, Integrated Maritime Systems, Surveillance & Strike Systems, Communications & Microwave Products and Precision Engagement Systems. Contract liabilities increased by $39 million primarily due to advances received by Defense Training Solutions and Special Programs. The Company did not recognize any impairment losses on contract assets during the quarterly period ended March 29, 2019 . For the quarterly period ended March 29, 2019 , the Company recognized sales of $270 million related to its contract liabilities at December 31, 2018 . The components of contract assets are presented in the table below. March 29, December 31, (in millions) Unbilled contract receivables, gross $ 3,035 $ 2,716 Unliquidated progress payments and advances (1,300 ) (1,126 ) Total contract assets $ 1,735 $ 1,590

Inventories

Inventories	3 Months Ended
	Mar. 29, 2019
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. March 29, December 31, (in millions) Raw materials, components and sub-assemblies $ 372 $ 351 Work in process 335 330 Finished goods 189 198 Total $ 896 $ 879 Inventories at March 29, 2019 included G&A costs of $35 million . G&A costs incurred and recorded in inventories totaled $301 million during the quarterly period ended March 29, 2019 , and G&A costs charged to expense from inventories totaled $295 million during the quarterly period ended March 29, 2019 .

Goodwill and Identifiable Intan

Goodwill and Identifiable Intangible Assets	3 Months Ended
	Mar. 29, 2019
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 $ 2,660 $ 2,004 $ 2,248 $ 6,912 Accumulated impairment losses (46 ) (15 ) (43 ) (104 ) December 31, 2018 2,614 1,989 2,205 6,808 Business acquisitions (1) — 2 — 2 Foreign currency translation adjustments 4 3 9 16 March 29, 2019 2,618 1,994 2,214 6,826 Goodwill 2,664 2,009 2,257 6,930 Accumulated impairment losses (46 ) (15 ) (43 ) (104 ) $ 2,618 $ 1,994 $ 2,214 $ 6,826 __________________ (1) The increase for the C&NS segment was due to the purchase price allocation adjustment for the ASV Global business acquisition. 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 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. March 29, 2019 December 31, 2018 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 17 $ 468 $ 295 $ 173 $ 468 $ 288 $ 180 Technology 10 245 137 108 245 132 113 Other 12 49 18 31 49 18 31 Total subject to amortization 762 450 312 762 438 324 IPR&D indefinite 66 — 66 66 — 66 Total $ 828 $ 450 $ 378 $ 828 $ 438 $ 390 The table below presents amortization expense recorded by the Company for its identifiable intangible assets. First Quarter Ended March 29, March 30, (in millions) Amortization expense $ 12 $ 11 Based on gross carrying amounts at March 29, 2019 , the Company’s estimate of amortization expense for identifiable intangible assets for the years ending December 31, 2019 through 2023 is presented in the table below. Year Ending December 31, 2019 2020 2021 2022 2023 (in millions) Estimated amortization expense $ 51 $ 47 $ 42 $ 37 $ 28

Other Current Liabilities and O

Other Current Liabilities and Other Liabilities	3 Months Ended
	Mar. 29, 2019
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. March 29, December 31, (in millions) Other current liabilities: Operating lease liabilities $ 74 $ — Accrued product warranty costs 61 66 Estimated costs in excess of estimated contract value to complete contracts in process in a loss position 46 40 Accrued interest 36 18 Estimated contingent purchase price payable for acquired businesses (see Note 14) 10 10 Other 137 154 Total other current liabilities $ 364 $ 288 The table below presents the components of other liabilities. March 29, December 31, (in millions) Other liabilities: Non-current income taxes payable (see Note 10) $ 159 $ 161 Deferred compensation 54 53 Contract liabilities (see Note 5) 28 31 Notes payable and other debt 24 22 Accrued product warranty costs 21 22 Accrued workers' compensation 21 20 Estimated contingent purchase price payable for acquired businesses (see Note 14) 6 10 Other 102 117 Total other liabilities $ 415 $ 436 The table below presents the changes in the Company’s accrued product warranty costs. First Quarter Ended March 29, March 30, (in millions) Accrued product warranty costs: Balance at January 1 $ 88 $ 99 Accruals for product warranties issued during the period 14 14 Changes to accruals for product warranties existing before January 1 (1 ) 1 Settlements made during the period (19 ) (14 ) Balance at end of period $ 82 $ 100

Debt

Debt	3 Months Ended
	Mar. 29, 2019
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. March 29, December 31, (in millions) Borrowings under Revolving Credit Facility (1) $ — $ — 4.95% Senior Notes due 2021 650 650 3.85% Senior Notes due 2023 800 800 3.95% Senior Notes due 2024 350 350 3.85% Senior Notes due 2026 550 550 4.40% Senior Notes due 2028 1,000 1,000 Principal amount of long-term debt (2) 3,350 3,350 Unamortized discounts (7 ) (7 ) Deferred debt issue costs (21 ) (22 ) Carrying amount of long-term debt $ 3,322 $ 3,321 __________________ (1) During the quarterly period ended March 29, 2019 , L3 had no borrowings or repayments under the Credit Facility. At March 29, 2019 , L3 had the full availability of its $1 billion Credit Facility. (2) With respect to the Company’s outstanding senior notes, 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.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 29, 2019
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 March 29, 2019 , the statutes of limitations for the Company’s U.S. Federal income tax returns for the years ended December 31, 2012, 2013, 2015, 2016 and 2017 were open. The effective income tax rate for the quarterly period ended March 29, 2019 increased to 14.2% , compared to 11.1% for the quarterly period ended March 30, 2018 . The increase was driven by a reduction in tax benefits from equity compensation partially offset by an increased tax benefit on export sales. At March 29, 2019 , the Company anticipated that unrecognized tax benefits will decrease by approximately $30 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 $15 million ( $11 million after income taxes) at March 29, 2019 and December 31, 2018 , and potential penalties of $8 million at March 29, 2019 and $9 million at December 31, 2018 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive (Loss) Income (AOCI)	3 Months Ended
	Mar. 29, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive (Loss) Income (AOCI)	Accumulated Other Comprehensive (Loss) Income (AOCI) The changes in the AOCI balances, including amounts reclassified from AOCI into net income, are presented in the table below. Foreign currency translation Unrealized (losses) gains on hedging instruments Unrecognized (losses) gains and prior service cost, net Total accumulated other comprehensive loss (in millions) Balance at December 31, 2018 $ (136 ) $ (10 ) $ (579 ) $ (725 ) Other comprehensive income (loss) before reclassifications, net of tax 23 (5 ) — 18 Amounts reclassified from AOCI, net of tax — (1 ) 7 6 Net current period other comprehensive income (loss) 23 (6 ) 7 24 Balance at March 29, 2019 $ (113 ) $ (16 ) $ (572 ) $ (701 ) Balance at December 31, 2017 $ (54 ) $ 9 $ (646 ) $ (691 ) Other comprehensive income before reclassifications, net of tax 33 — — 33 Amounts reclassified from AOCI, net of tax — (1 ) 14 13 Net current period other comprehensive income (loss) 33 (1 ) 14 46 Balance at March 30, 2018 $ (21 ) $ 8 $ (632 ) $ (645 ) Further details regarding the amounts reclassified from AOCI into net income are presented in the table below. ASU 2017-12 did not have an impact in the Company's presentation of the earnings effect of hedging instruments in the income statement. Amount Reclassified from AOCI (a) Affected Line Item in the Unaudited Condensed Consolidated Statements of Operations First Quarter Ended Details About AOCI Components March 29, March 30, (in millions) Gain on hedging instruments $ 1 $ 1 Cost of sales - Products 1 1 Income from continuing operations before income taxes — — Provision for income taxes $ 1 $ 1 Income from continuing operations Amortization of defined benefit pension and postretirement items: Net loss (b) $ (9 ) $ (18 ) Income from continuing operations before income taxes 2 4 Provision for income taxes $ (7 ) $ (14 ) Income from continuing operations Total reclassification for the period $ (6 ) $ (13 ) 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 19 for additional information).

Equity

Equity	3 Months Ended
	Mar. 29, 2019
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. 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 April 26, 2019 . The last repurchase of shares was in July 2018. In connection with the planned merger with Harris Corporation (see Note 1 ), the Company suspended the share repurchase program. On February 12, 2019 , L3’s Board of Directors declared a quarterly cash dividend of $ 0.85 per share, paid on March 15, 2019 to shareholders of record at the close of business on March 1, 2019 . During the quarterly period ended March 29, 2019 , the Company paid $70 million of cash dividends, including $3 million net reduction of previously accrued dividends for employee-held stock awards.

L3's Earnings Per Share

L3's Earnings Per Share	3 Months Ended
	Mar. 29, 2019
Earnings Per Share [Abstract]
L3's Earnings Per Share	L3’s Earnings Per Share A reconciliation of basic and diluted Earnings Per Share (EPS) is presented in the table below. First Quarter Ended March 29, March 30, (in millions, except per share data) Reconciliation of net income: Net income $ 223 $ 208 Net income from continuing operations attributable to noncontrolling interests (6 ) (5 ) Net income attributable to L3’s common shareholders $ 217 $ 203 Earnings attributable to L3’s common shareholders: Continuing operations $ 217 $ 187 Discontinued operations, net of income tax — 16 Net income attributable to L3’s common shareholders $ 217 $ 203 Earnings per share attributable to L3’s common shareholders: Basic: Weighted average common shares outstanding 79.2 78.2 Basic earnings per share: Continuing operations $ 2.74 $ 2.40 Discontinued operations, net of income tax — 0.20 Net income $ 2.74 $ 2.60 Diluted: Common and potential common shares: Weighted average common shares outstanding 79.2 78.2 Effect of dilutive securities 0.8 1.7 Common and potential common shares 80.0 79.9 Diluted earnings per share: Continuing operations $ 2.71 $ 2.34 Discontinued operations, net of income tax — 0.20 Net income $ 2.71 $ 2.54 The computation of diluted EPS excludes 0.5 million shares for the quarterly period ended March 29, 2019 and 0.3 million shares for the quarterly period ended March 30, 2018 for share-based payment awards as they were anti-dilutive.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 29, 2019
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. March 29, 2019 December 31, 2018 Description Level 1 (1) Level 2 (2) Level 3 (3) Level 1 (1) Level 2 (2) Level 3 (3) (in millions) Assets Cash equivalents $ 756 $ — $ — $ 660 $ — $ — Derivatives (foreign currency forward contracts) — 3 — — 1 — Total assets $ 756 $ 3 $ — $ 660 $ 1 $ — Liabilities Derivatives (foreign currency forward contracts) $ — $ 9 $ — $ — $ 17 $ — Derivatives (treasury lock contracts) (4) — 16 — — — — Contingent consideration — — 16 — — 20 Total liabilities $ — $ 25 $ 16 $ — $ 17 $ 20 __________________ (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, interest rates and consideration of non-performance risk. (3) Level 3 is based on pricing inputs that are not observable and not corroborated by market data. (4) See Note 16 for information regarding the treasury lock contracts. 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. 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 cost of sales in the unaudited condensed consolidated statements of operations. The table below presents the changes to contingent consideration obligations during the quarterly period ended March 29, 2019 . March 29, 2019 (in millions) Balance at beginning of period $ 20 Changes in fair value of contingent consideration, net (4 ) Balance at end of period $ 16

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 29, 2019
Investments, All Other Investments [Abstract]
Financial Instruments	Financial Instruments At March 29, 2019 and December 31, 2018 , the Company’s financial instruments consisted primarily of cash and cash equivalents, billed receivables, trade accounts payable, senior notes, foreign currency forward contracts and treasury lock 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. March 29, 2019 December 31, 2018 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value (in millions) Senior notes (1) $ 3,322 $ 3,451 $ 3,321 $ 3,355 Foreign currency forward contracts (2) $ (6 ) $ (6 ) $ (16 ) $ (16 ) Treasury lock contracts (3) $ (16 ) $ (16 ) $ — $ — __________________ (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 16 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts. (3) The Company measures the fair values of treasury lock contracts based on 10-year treasury rates. See Note 16 for additional disclosures regarding the notional amounts and fair values of treasury lock contracts.

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Mar. 29, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The Company’s derivative financial instruments include foreign currency forward contracts and treasury lock 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 U.S. dollar, the Canadian dollar, the Euro, the British pound, the United Arab Emirates dirham 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 March 29, 2019 . Currency Notional Amounts (in millions) U.S. dollar $ 197 Canadian dollar 85 Euro 75 British pound 11 United Arab Emirates dirham 9 New Zealand dollar 9 Total $ 386 At March 29, 2019 , the Company’s foreign currency forward contracts had maturities through 2023. Treasury Lock Contracts. The Company uses treasury lock contracts principally to reduce its exposure to market risks from changes in interest rates. The Company does not enter into or hold interest rate swap contracts for speculative or trading purposes. The Company is exposed to the impact of interest rate changes primarily through its borrowing activities. The Company’s treasury lock contracts are designated for hedge accounting. In January 2019, the Company entered into two treasury lock contracts to fix the treasury yield component of the interest cost of forecasted refinancing associated with the $650 million of 4.95% Senior Notes due 2021. The treasury lock contracts are scheduled to terminate on February 12, 2021. The Company has designated these treasury lock contracts as cash flow hedges of an anticipated transaction. Any unrealized gains and losses associated with the treasury locks are recorded as a component of accumulated other comprehensive income. Unrealized gains occur when interest rates increase, conversely, any unrealized losses occur when interest rates decline. Upon termination of the treasury lock contracts, the Company will recognize any unrealized gains or losses over the life of the related financing arrangement. As of March 29, 2019 the Company recorded unrealized hedging losses of $12 million , net of taxes due to a decline in the 10-year treasury rate. The table below presents the location of the Company’s derivative instruments recorded at fair value on the condensed consolidated balance sheets. March 29, 2019 December 31, 2018 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) $ 2 $ 1 $ 7 $ 2 $ 1 $ — $ 13 $ 4 Treasury lock contracts (1) — — — 16 — — — — Total derivative instruments $ 2 $ 1 $ 7 $ 18 $ 1 $ — $ 13 $ 4 __________________ (1) See Note 14 for a description of the fair value hierarchy related to the Company’s foreign currency forward contracts and treasury lock contracts. The effects from foreign currency forward contracts on the unaudited condensed consolidated statements of operations were a pre-tax gain of $1 million for each of the quarterly periods ended March 29, 2019 and March 30, 2018 . At March 29, 2019 , the estimated net amount of existing losses that are expected to be reclassified into income within the next 12 months was $5 million .

Leases

Leases	3 Months Ended
	Mar. 29, 2019
Leases [Abstract]
Leases	Leases As discussed in Note 2 , effective January 1, 2019, the Company adopted ASC 842. The Company’s operating and finance leases at March 29, 2019 were for real estate such as office space, warehouses, manufacturing, research and development facilities, and land, and equipment. Finance leases were not material as of March 29, 2019 and were therefore not included in the disclosures below. The components of the Company's lease expense are presented in the table below. First Quarter Ended March 29, 2019 (in millions) Operating lease cost $ 29 Short-term and equipment lease cost 1 Variable lease cost 4 Sublease income (1 ) Net lease cost $ 33 Supplemental operating lease balance sheet information is presented in the table below. March 29, 2019 (in millions) Operating lease right-of-use assets $ 618 Other current liabilities $ 74 Operating lease liabilities 569 Total operating lease liabilities $ 643 Other supplemental information related to the Company's leases is presented in the table below. First Quarter Ended (in millions, except lease term and discount rate) March 29, 2019 Cash paid for amounts included in the measurement of operating lease liabilities $ 33 Right-of-use assets obtained in exchange for new operating lease liabilities $ 3 Weighted average remaining lease term - operating leases (in years) 10.9 Weighted average discount rate - operating leases 4.4 % The following table presents future lease payments under non-cancelable leases as of March 29, 2019 . Operating Leases March 29, 2019 (in millions) 2019 $ 76 2020 91 2021 81 2022 73 2023 64 Thereafter 437 Total future lease payments required 822 Less: imputed interest 179 Total $ 643 As of March 29, 2019 , the Company had $115 million of additional operating leases for real estate facilities that have not yet commenced. These leases will commence between 2019 and 2020 with lease terms of 10 to 15 years. As discussed in Note 2 , the Company has adopted ASC 842 using the optional transition method presenting prior period amounts and disclosures under ASC 840. The following presents the Company's future minimum lease payments for operating leases under ASC 840 at December 31, 2018. Operating Leases December 31, 2018 (in millions) 2019 $ 115 2020 134 2021 82 2022 73 2023 65 Thereafter 506 Total minimum payments required 975 Sublease rentals under non-cancelable leases (7 ) Net minimum payments required $ 968 Rent expense and sublease rental income were $105 million and $2 million , respectively, for the year ended December 31, 2018.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 29, 2019
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 March 29, 2019 , 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's insurers have accepted defense of the matter and retained counsel. As previously disclosed, the four lawsuits challenging the merger of the Company and Harris were filed by purported L3 shareholders. These lawsuits have been dismissed by the plaintiffs. They were: (1) an individual action captioned Stein v. L3 Technologies, Inc., et al. , in the Southern District of New York, naming L3 and the members of L3’s board of directors - Plaintiff voluntarily dismissed this matter with prejudice on March 18, 2019; (2) a putative class action captioned Raul v. L3 Technologies, Inc., et al. , in the Southern District of New York, naming L3 and the members of L3’s board of directors - Plaintiff voluntarily dismissed this matter with prejudice on March 12, 2019; (3) a putative class action captioned Gross v. L3 Technologies, Inc., et al. , in the Southern District of New York, naming L3 and the members of L3’s board of directors - Plaintiff voluntarily dismissed this matter with prejudice on March 18, 2019; and (4) a putative class action captioned Kent v. L3 Technologies, Inc., et al. , in the District of Delaware, naming L3, the members of L3’s board of directors, Harris and Merger Sub - Plaintiff voluntarily dismissed this matter with prejudice on March 18, 2019.

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	3 Months Ended
	Mar. 29, 2019
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 First Quarter Ended First Quarter Ended March 29, March 30, March 29, March 30, (in millions) Components of net periodic benefit cost: Service cost $ 6 $ 26 $ 1 $ — Interest cost 40 36 1 1 Expected return on plan assets (49 ) (56 ) (1 ) (1 ) Amortization of prior service credits (1 ) — — — Amortization of net loss (gains) 11 19 (1 ) (1 ) Curtailment loss (1) 2 — — — Net periodic benefit cost $ 9 $ 25 $ — $ (1 ) __________________ (1) During the quarterly period ended March 29, 2019, the Company recognized a $2 million pension curtailment loss related to severance and restructuring activities in the C&NS 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 $8 million to its pension plans and $1 million to its other postretirement benefit plans during the quarterly period ended March 29, 2019 . The Company expects to contribute an additional $72 million to its pension plans and $7 million to its other postretirement benefit plans during the remainder of 2019 .

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 29, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation During the quarterly period ended March 29, 2019 , the Company granted stock-based awards under the Amended and Restated 2008 Long Term Performance Plan in the form of restricted stock units. The stock-based compensation awards granted during the quarterly period ended March 29, 2019 are further discussed below. Restricted Stock Units. The Company granted 272,703 restricted stock units with a weighted average grant date fair value of $206.59 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 quarterly period ended March 29, 2019 , 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).

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Mar. 29, 2019
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information First Quarter Ended March 29, March 30, (in millions) Interest paid $ 18 $ 37 Income tax payments $ 20 $ 21 Income tax refunds $ 5 $ 2

Segment Information and Disaggr

Segment Information and Disaggregation of Net Sales	3 Months Ended
	Mar. 29, 2019
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, merger and acquisition related expenses, gains or losses related to business divestitures and certain other items that are excluded by management for purposes of evaluating the operating performance of the Company’s business segments. The tables below present net sales, operating income, depreciation and amortization and total assets by reportable segment. First Quarter Ended March 29, March 30, (in millions) Net Sales: ISRS $ 1,259 $ 1,018 C&NS 793 713 Electronic Systems 670 659 Elimination of intercompany sales (22 ) (19 ) Consolidated total $ 2,700 $ 2,371 Operating Income: ISRS $ 130 $ 93 C&NS 84 64 Electronic Systems 97 94 Segment total 311 251 Merger, acquisition and divestiture related expenses and losses (18 ) — Consolidated total $ 293 $ 251 Depreciation and amortization: ISRS $ 23 $ 21 C&NS 16 17 Electronic Systems 19 18 Consolidated total $ 58 $ 56 March 29, December 31, (in millions) Total Assets: ISRS $ 4,823 $ 4,749 C&NS 3,991 3,641 Electronic Systems 4,257 4,128 Corporate 1,192 1,000 Consolidated total $ 14,263 $ 13,518 Disaggregation of Total Net Sales . The Company disaggregates its sales from contracts with customers by: (1) end customer, (2) contract type, (3) deliverable type and (4) revenue recognition method for each of its segments. 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 63% and 65% of the Company’s consolidated sales for the quarterly periods ended March 29, 2019 and March 30, 2018 , respectively, and indirect sales as a subcontractor or supplier represented the remaining 37% and 35% , respectively. The tables below present total net sales disaggregated by end customer. First Quarter Ended March 29, 2019 End Customer ISRS C&NS Electronic Systems Consolidated L3 (in millions) Total DoD $ 921 $ 593 $ 335 $ 1,849 Other U.S. Government 26 25 28 79 Total U.S. Government 947 618 363 1,928 Foreign governments (1) 254 86 57 397 Commercial — foreign 20 31 160 211 Commercial — domestic 32 50 82 164 Total $ 1,253 $ 785 $ 662 $ 2,700 First Quarter Ended March 30, 2018 End Customer ISRS C&NS Electronic Systems Consolidated L3 (in millions) Total DoD $ 726 $ 516 $ 320 $ 1,562 Other U.S. Government 30 27 36 93 Total U.S. Government 756 543 356 1,655 Foreign governments (1) 205 83 43 331 Commercial — foreign 29 26 162 217 Commercial — domestic 26 55 87 168 Total $ 1,016 $ 707 $ 648 $ 2,371 __________________ (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. First Quarter Ended March 29, 2019 Contract Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Fixed-price (1) $ 908 $ 577 $ 545 $ 2,030 Cost-plus (2) 295 189 107 591 Time-and-material 50 19 10 79 Total sales $ 1,253 $ 785 $ 662 $ 2,700 First Quarter Ended March 30, 2018 Contract Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Fixed-price (1) $ 639 $ 506 $ 547 $ 1,692 Cost-plus (2) 324 179 93 596 Time-and-material 53 22 8 83 Total sales $ 1,016 $ 707 $ 648 $ 2,371 __________________ (1) Includes fixed-price incentive fee type contracts, which contributed approximately 1% and 2% to the Company's total net sales for the quarterly periods ended March 29, 2019 and March 30, 2018 , respectively. (2) Includes cost-plus award and incentive fee type contracts, which contributed approximately 3% and 4% to the Company's total net sales for the quarterly periods ended March 29, 2019 and March 30, 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. First Quarter Ended March 29, 2019 Sales by Deliverable Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Products $ 855 $ 606 $ 471 $ 1,932 Services 398 179 191 768 Total sales $ 1,253 $ 785 $ 662 $ 2,700 First Quarter Ended March 30, 2018 Sales by Deliverable Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Products $ 655 $ 532 $ 459 $ 1,646 Services 361 175 189 725 Total sales $ 1,016 $ 707 $ 648 $ 2,371 Revenue Recognition Method: The tables below present total net sales disaggregated based on the revenue recognition method applied. First Quarter Ended March 29, 2019 Revenue Recognition Method ISRS C&NS Electronic Systems Consolidated L3 (in millions) Over time (cost-to-cost method) $ 981 $ 647 $ 417 $ 2,045 Point in time 225 115 163 503 Output method 24 5 67 96 Billing method 23 18 15 56 Total sales $ 1,253 $ 785 $ 662 $ 2,700 First Quarter Ended March 30, 2018 Revenue Recognition Method ISRS C&NS Electronic Systems Consolidated L3 (in millions) Over time (cost-to-cost method) $ 807 $ 576 $ 419 $ 1,802 Point in time 157 103 172 432 Output method 16 7 51 74 Billing method 36 21 6 63 Total sales $ 1,016 $ 707 $ 648 $ 2,371

Severance and Restructuring Rel

Severance and Restructuring Related Costs	3 Months Ended
	Mar. 29, 2019
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 $6 million of severance and restructuring related costs with respect to approximately 300 employees during the quarterly period ended March 29, 2019 . During the year ended December 31, 2018 , the Company recorded a total of $26 million of severance and restructuring related costs with respect to approximately 800 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. First Quarter Ended March 29, March 30, (in millions) Reportable Segment ISRS $ 1 $ 1 C&NS 4 5 Electronic Systems 1 2 Consolidated $ 6 $ 8 The Company had severance and restructuring related liabilities of $9 million and $14 million included in other current liabilities on the Company’s balance sheets at March 29, 2019 and December 31, 2018 , respectively. The remaining liability balance at March 29, 2019 is expected to be paid primarily by the end of 2019. The table below presents the change to the Company’s severance and restructuring related liability during the quarterly period ended March 29, 2019 . March 29, 2019 (in millions) Balance at beginning of period $ 14 Additional provisions 6 Cash payments (11 ) Balance at end of period $ 9

Condensed Combining Financial I

Condensed Combining Financial Information of L3 and Its Subsidiaries	3 Months Ended
	Mar. 29, 2019
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, is guaranteed, on a joint and several, full and unconditional basis, by certain of its 100% owned domestic subsidiaries (the Guarantor Subsidiaries). See Note 10 to the audited consolidated financial statements for the year ended December 31, 2018 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 March 29, 2019 Current assets: Cash and cash equivalents $ 856 $ 19 $ 309 $ (76 ) $ 1,108 Billed receivables, net 230 268 306 — 804 Contract assets 580 953 202 — 1,735 Inventories 369 268 259 — 896 Prepaid expenses and other current assets 127 180 55 — 362 Total current assets 2,162 1,688 1,131 (76 ) 4,905 Goodwill 2,124 3,007 1,695 — 6,826 Other assets 1,004 954 574 — 2,532 Investment in and amounts due from consolidated subsidiaries 6,049 6,534 — (12,583 ) — Total assets $ 11,339 $ 12,183 $ 3,400 $ (12,659 ) $ 14,263 Current liabilities $ 797 $ 1,036 $ 675 $ (76 ) $ 2,432 Amounts due to consolidated subsidiaries — — 445 (445 ) — Other long-term liabilities 1,169 963 259 — 2,391 Long-term debt 3,322 — — — 3,322 Total liabilities 5,288 1,999 1,379 (521 ) 8,145 L3 shareholders’ equity 6,051 10,184 2,021 (12,205 ) 6,051 Noncontrolling interests — — — 67 67 Total equity 6,051 10,184 2,021 (12,138 ) 6,118 Total liabilities and equity $ 11,339 $ 12,183 $ 3,400 $ (12,659 ) $ 14,263 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) At December 31, 2018 Current assets: Cash and cash equivalents $ 756 $ 21 $ 306 $ (17 ) $ 1,066 Billed receivables, net 291 341 287 — 919 Contract assets 562 833 195 — 1,590 Inventories 378 258 243 — 879 Prepaid expenses and other current assets 127 166 63 — 356 Total current assets 2,114 1,619 1,094 (17 ) 4,810 Goodwill 2,124 3,009 1,675 — 6,808 Other assets 690 765 445 — 1,900 Investment in and amounts due from consolidated subsidiaries 5,931 6,912 — (12,843 ) — Total assets $ 10,859 $ 12,305 $ 3,214 $ (12,860 ) $ 13,518 Current liabilities $ 821 $ 955 $ 688 $ (17 ) $ 2,447 Amounts due to consolidated subsidiaries — — 417 (417 ) — Other long-term liabilities 878 804 161 — 1,843 Long-term debt 3,321 — — — 3,321 Total liabilities 5,020 1,759 1,266 (434 ) 7,611 L3 shareholders’ equity 5,839 10,546 1,948 (12,494 ) 5,839 Noncontrolling interests — — — 68 68 Total equity 5,839 10,546 1,948 (12,426 ) 5,907 Total liabilities and equity $ 10,859 $ 12,305 $ 3,214 $ (12,860 ) $ 13,518 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) Condensed Combining Statements of Operations: For the quarter ended March 29, 2019: Total net sales $ 904 $ 1,418 $ 462 $ (84 ) $ 2,700 Total operating costs and expenses (785 ) (1,312 ) (376 ) 84 (2,389 ) Merger, acquisition and divestiture related expenses and losses (18 ) — — — (18 ) Operating income 101 106 86 — 293 Interest expense (37 ) — — — (37 ) Interest and other income, net 3 1 — — 4 Income from continuing operations before income taxes 67 107 86 — 260 Provision for income taxes (10 ) (15 ) (12 ) — (37 ) Equity in net income of consolidated subsidiaries 160 36 — (196 ) — Net income 217 128 74 (196 ) 223 Net income attributable to noncontrolling interests — — — (6 ) (6 ) Net income attributable to L3 $ 217 $ 128 $ 74 $ (202 ) $ 217 Comprehensive income attributable to L3 $ 241 $ 158 $ 101 $ (259 ) $ 241 For the quarter ended March 30, 2018: Total net sales $ 807 $ 1,239 $ 422 $ (97 ) $ 2,371 Total operating costs and expenses (722 ) (1,155 ) (340 ) 97 (2,120 ) Operating income 85 84 82 — 251 Interest expense (41 ) — — — (41 ) Interest and other income, net 5 — 1 — 6 Income from continuing operations before income taxes 49 84 83 — 216 Provision for income taxes (6 ) (9 ) (9 ) — (24 ) Equity in net income of consolidated subsidiaries 144 47 — (191 ) — Income from continuing operations 187 122 74 (191 ) 192 Income from discontinued operations, net of income taxes 16 — — — 16 Net income 203 122 74 (191 ) 208 Net income attributable to noncontrolling interests — — — (5 ) (5 ) Net income attributable to L3 $ 203 $ 122 $ 74 $ (196 ) $ 203 Comprehensive income attributable to L3 $ 249 $ 153 $ 107 $ (260 ) $ 249 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) Condensed Combining Statements of Cash Flows For the quarter ended March 29, 2019: Operating activities: Net cash from operating activities from continuing operations $ 101 $ 55 $ 18 $ — $ 174 Investing activities: Proceeds from sale of businesses, net of closing date cash balances 1 — — — 1 Other investing activities (42 ) (19 ) (14 ) — (75 ) Net cash used in investing activities from continuing operations (41 ) (19 ) (14 ) — (74 ) Financing activities: Dividends paid (70 ) — — — (70 ) Other financing activities 91 (38 ) (4 ) (59 ) (10 ) Net cash from (used in) financing activities from continuing operations 21 (38 ) (4 ) (59 ) (80 ) Effect of foreign currency exchange rate changes on cash — — 3 — 3 Net increase in cash and cash equivalents of discontinued operations 19 — — — 19 Net increase (decrease) in cash 100 (2 ) 3 (59 ) 42 Cash and cash equivalents, beginning of the period 756 21 306 (17 ) 1,066 Cash and cash equivalents, end of the period $ 856 $ 19 $ 309 $ (76 ) $ 1,108 For the quarter ended March 30, 2018: Operating activities: Net cash from (used in) operating activities from continuing operations $ 198 $ (204 ) $ (24 ) $ (5 ) $ (35 ) Investing activities: Other investing activities (62 ) (17 ) (4 ) — (83 ) Net cash used in investing activities from continuing operations (62 ) (17 ) (4 ) — (83 ) Financing activities: Common stock repurchased (119 ) — — — (119 ) Dividends paid (65 ) — — — (65 ) Other financing activities (196 ) 226 (50 ) 58 38 Net cash (used in) from financing activities from continuing operations (380 ) 226 (50 ) 58 (146 ) Effect of foreign currency exchange rate changes on cash — — 6 — 6 Net decrease in cash and cash equivalents of discontinued operations (30 ) — — — (30 ) Net (decrease) increase in cash (274 ) 5 (72 ) 53 (288 ) Cash and cash equivalents, beginning of the period 432 14 287 (71 ) 662 Cash and cash equivalents, end of the period $ 158 $ 19 $ 215 $ (18 ) $ 374

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 29, 2019
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 voting control are accounted for using the equity method. Investments over which the Company does not have significant influence are accounted for using the cost method. For the classification of 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, 2018 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 cost of sales during the reporting period. The most significant of these estimates and assumptions relate to sales, profit and loss recognition for 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 realizable value, pension and post-retirement benefit obligations, stock-based employee compensation expense, income taxes, including the valuations of deferred tax assets, litigation reserves, useful lives and valuation of recorded amounts of long-lived assets, identifiable intangible assets and goodwill. Changes in estimates are reflected in the periods during which they become known. Actual amounts may differ from these estimates and could differ materially.
Revenue Recognition	Revenue Recognition 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. 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. The Company also records sales from performance obligations satisfied at a point in time, which are typically for standard goods. See Note 22 for additional information regarding the composition of the Company’s net sales. Revisions or adjustments to estimates of the transaction price, estimated costs at completion and estimated profit or loss of a performance obligation may be 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 in some cases result in liabilities to complete contracts in a loss position. Net sales recognized from the Company's performance obligations partially satisfied in prior periods were $83 million for the quarterly period ended March 29, 2019 and relate to revisions in contract estimates. The aggregate impact of net changes in contract estimates is presented in the table below. First Quarter Ended March 29, March 30, (in millions, except per share data) Operating income $ 66 $ 50 Diluted earnings per share $ 0.63 $ 0.48 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 quarterly period s ended March 29, 2019 and March 30, 2018 . First Quarter Ended March 29, March 30, Over time (cost-to-cost method) 76 % 76 % Point in time 19 % 18 % Output method 3 % 3 % Billing method 2 % 3 % Total 100 % 100 % Remaining Performance Obligations As of March 29, 2019 , the Company had $12.0 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 $6.5 billion during the remainder of 2019 , $3.4 billion in 2020 , $1.1 billion in 2021 and $1.0 billion in the periods thereafter.
Leases	Leases Effective January 1, 2019, the Company adopted ASU 2016-02 Leases, (ASC 842), using the optional transition method. In accordance with the optional transition method, the Company initially applied the new standard for existing leases as of January 1, 2019. In addition, in accordance with the optional transition method prior period amounts and disclosures are presented under ASC 840. The cumulative effect of applying ASC 842 was an increase of $640 million to the Company's assets and liabilities. In accordance with ASC 842, the Company recognizes lease assets and liabilities on the balance sheet for operating and finance leases under which the Company is a lessee, except for equipment leases and, as permitted by a practical expedient under the standard, leases with a term of 12 months or less. Equipment leases were not material at January 1, 2019 or March 29, 2019 and therefore not recognized on the balance sheet for these periods. The Company recognizes a lease expense on a straight-line basis over the lease term for equipment leases and leases with a term of 12 months or less. The Company classifies operating lease assets as operating lease right-of-use (ROU) assets and operating lease liabilities in other current liabilities for obligations due within 12 months, or operating lease liabilities for obligations due longer than 12 months. Finance lease assets are classified in property, plant and equipment. Finance lease liabilities are classified in other current liabilities or other liabilities depending on when the obligation is due. Lease assets and liabilities are recognized based on the present value of future lease payments. Lease payments primarily include rent and insurance costs (lease components). The Company's leases also include non-lease components such as real estate taxes and common-area maintenance costs. The Company elected the practical expedient to account for lease and non-lease components as a single component. In certain of the Company's leases, the non-lease components are variable and in accordance with the standard are therefore excluded from lease payments to determine the lease asset. The present value of future lease payments is determined using the Company's incremental borrowing rate at lease commencement over the expected lease term. The Company uses its incremental borrowing rate because the Company's leases do not provide an implicit lease rate. The expected lease term represents the number of years the Company expects to lease the property, including options to extend or terminate the lease when it is reasonably certain that the Company will exercise such option. For operating leases, the lease expense is recognized on a straight-line basis over the expected lease term on the statement of operations as an operating cost. For finance leases, the asset is amortized on a straight-line basis over the lease term, and interest on the lease liability is recognized in interest expense. The amortization of lease assets for the Company's finance leases and interest expense were not material for the three months ended March 29, 2019 .
Lessor	Lessor The Company is a lessor for certain arrangements for flight simulators. These leases meet the criteria for operating lease classification. Lease income associated with these leases is not material.
General and Administrative Expenses	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 $71 million and $75 million for the quarterly period s ended March 29, 2019 and March 30, 2018 , 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.

New Accounting Standards Impl_2

New Accounting Standards Implemented (Policies)	3 Months Ended
	Mar. 29, 2019
Accounting Changes and Error Corrections [Abstract]
New Accounting Standards Implemented	In February 2018, the Financial Accounting Standards Board (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 Company adopted ASU 2018-02 as of January 1, 2019 and elected not to reclassify amounts from AOCI for the stranded tax effects of U.S. Tax Reform. The adoption of ASU 2018-02 did not have any impact on the Company’s 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. 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 adopted ASU 2017-12 effective January 1, 2019. The adoption of this standard did not have a material effect on the Company's financial position, results of operations or cash flows. In February 2016, the FASB issued ASC 842 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 adopted the standard as of January 1, 2019.

Basis of Presentation (Tables)

Basis of Presentation (Tables)	3 Months Ended
	Mar. 29, 2019
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. First Quarter Ended March 29, March 30, (in millions, except per share data) Operating income $ 66 $ 50 Diluted earnings per share $ 0.63 $ 0.48
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 quarterly period s ended March 29, 2019 and March 30, 2018 . First Quarter Ended March 29, March 30, Over time (cost-to-cost method) 76 % 76 % Point in time 19 % 18 % Output method 3 % 3 % Billing method 2 % 3 % Total 100 % 100 %
Impact of Adoption of New Accounting Pronouncement	The aggregate impact of net changes in contract estimates is presented in the table below. First Quarter Ended March 29, March 30, (in millions, except per share data) Operating income $ 66 $ 50 Diluted earnings per share $ 0.63 $ 0.48

Acquisitions, Divestitures an_2

Acquisitions, Divestitures and Discontinued Operations (Tables)	3 Months Ended
	Mar. 29, 2019
Business Combinations [Abstract]
Unaudited Pro Forma Statements of Operations Data	The following unaudited pro forma Statement of Operations data presents the combined results of the Company and its business acquisitions completed during the year ended December 31, 2018 , assuming that the business acquisitions completed during 2018 had occurred on January 1, 2017 . The unaudited pro forma Statement of Operations data below includes adjustments for additional amortization expense related to acquired intangible assets and depreciation assuming the 2018 acquisitions had occurred on January 1, 2017 . First Quarter Ended March 30, 2018 (in millions, except per share data) Pro forma net sales $ 2,404 Pro forma income from continuing operations attributable to L3 $ 191 Pro forma net income attributable to L3 $ 207 Pro forma diluted earnings per share from continuing operations $ 2.39 Pro forma diluted earnings per share $ 2.59
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. First Quarter Ended March 30, 2018 (in millions) Net sales $ 33 Income from continuing operations before income taxes $ 1
Disposal Groups, Including Discontinued Operations	As discussed in Note 1 , on June 29, 2018, the Company completed the sale of its Vertex Aerospace businesses. 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) total L3 consolidated net assets and (2) L3 consolidated total debt. First Quarter Ended March 30, 2018 (in millions) Net sales $ 371 Operating costs and expenses (349 ) Operating income from discontinued operations 22 Interest expense allocated to discontinued operations (1 ) Income from discontinued operations before income taxes 21 Income tax expense (5 ) Income from discontinued operations, net of income taxes $ 16

Contract Assets and Contract _2

Contract Assets and Contract Liabilities (Tables)	3 Months Ended
	Mar. 29, 2019
Revenue from Contract with Customer [Abstract]
Rollforward of Net Contract Assets (Liabilities)	The table below presents the components of net contract assets. March 29, December 31, (in millions) Contract assets $ 1,735 $ 1,590 Contract liabilities — current (711 ) (669 ) Contract liabilities — non-current (28 ) (31 ) Net contract assets $ 996 $ 890
Components of Contract Assets	The components of contract assets are presented in the table below. March 29, December 31, (in millions) Unbilled contract receivables, gross $ 3,035 $ 2,716 Unliquidated progress payments and advances (1,300 ) (1,126 ) Total contract assets $ 1,735 $ 1,590

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 29, 2019
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. March 29, December 31, (in millions) Raw materials, components and sub-assemblies $ 372 $ 351 Work in process 335 330 Finished goods 189 198 Total $ 896 $ 879

Goodwill and Identifiable Int_2

Goodwill and Identifiable Intangible Assets (Tables)	3 Months Ended
	Mar. 29, 2019
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 $ 2,660 $ 2,004 $ 2,248 $ 6,912 Accumulated impairment losses (46 ) (15 ) (43 ) (104 ) December 31, 2018 2,614 1,989 2,205 6,808 Business acquisitions (1) — 2 — 2 Foreign currency translation adjustments 4 3 9 16 March 29, 2019 2,618 1,994 2,214 6,826 Goodwill 2,664 2,009 2,257 6,930 Accumulated impairment losses (46 ) (15 ) (43 ) (104 ) $ 2,618 $ 1,994 $ 2,214 $ 6,826 __________________ (1) The increase for the C&NS segment was due to the purchase price allocation adjustment for the ASV Global business acquisition.
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. March 29, 2019 December 31, 2018 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 17 $ 468 $ 295 $ 173 $ 468 $ 288 $ 180 Technology 10 245 137 108 245 132 113 Other 12 49 18 31 49 18 31 Total subject to amortization 762 450 312 762 438 324 IPR&D indefinite 66 — 66 66 — 66 Total $ 828 $ 450 $ 378 $ 828 $ 438 $ 390
Amortization Expense	The table below presents amortization expense recorded by the Company for its identifiable intangible assets. First Quarter Ended March 29, March 30, (in millions) Amortization expense $ 12 $ 11
Estimated Amortization Expense	Based on gross carrying amounts at March 29, 2019 , the Company’s estimate of amortization expense for identifiable intangible assets for the years ending December 31, 2019 through 2023 is presented in the table below. Year Ending December 31, 2019 2020 2021 2022 2023 (in millions) Estimated amortization expense $ 51 $ 47 $ 42 $ 37 $ 28

Other Current Liabilities and_2

Other Current Liabilities and Other Liabilities (Tables)	3 Months Ended
	Mar. 29, 2019
Other Liabilities Disclosure [Abstract]
Other Current Liabilities	The table below presents the components of other current liabilities. March 29, December 31, (in millions) Other current liabilities: Operating lease liabilities $ 74 $ — Accrued product warranty costs 61 66 Estimated costs in excess of estimated contract value to complete contracts in process in a loss position 46 40 Accrued interest 36 18 Estimated contingent purchase price payable for acquired businesses (see Note 14) 10 10 Other 137 154 Total other current liabilities $ 364 $ 288
Other Liabilities	The table below presents the components of other liabilities. March 29, December 31, (in millions) Other liabilities: Non-current income taxes payable (see Note 10) $ 159 $ 161 Deferred compensation 54 53 Contract liabilities (see Note 5) 28 31 Notes payable and other debt 24 22 Accrued product warranty costs 21 22 Accrued workers' compensation 21 20 Estimated contingent purchase price payable for acquired businesses (see Note 14) 6 10 Other 102 117 Total other liabilities $ 415 $ 436
Changes in Company's Accrued Product Warranty Costs	The table below presents the changes in the Company’s accrued product warranty costs. First Quarter Ended March 29, March 30, (in millions) Accrued product warranty costs: Balance at January 1 $ 88 $ 99 Accruals for product warranties issued during the period 14 14 Changes to accruals for product warranties existing before January 1 (1 ) 1 Settlements made during the period (19 ) (14 ) Balance at end of period $ 82 $ 100

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 29, 2019
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. March 29, December 31, (in millions) Borrowings under Revolving Credit Facility (1) $ — $ — 4.95% Senior Notes due 2021 650 650 3.85% Senior Notes due 2023 800 800 3.95% Senior Notes due 2024 350 350 3.85% Senior Notes due 2026 550 550 4.40% Senior Notes due 2028 1,000 1,000 Principal amount of long-term debt (2) 3,350 3,350 Unamortized discounts (7 ) (7 ) Deferred debt issue costs (21 ) (22 ) Carrying amount of long-term debt $ 3,322 $ 3,321 __________________ (1) During the quarterly period ended March 29, 2019 , L3 had no borrowings or repayments under the Credit Facility. At March 29, 2019 , L3 had the full availability of its $1 billion Credit Facility. (2) With respect to the Company’s outstanding senior notes, 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.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive (Loss) Income (AOCI) (Tables)	3 Months Ended
	Mar. 29, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Summary of AOCI Balances Including Amounts Reclassified from AOCI into Net Income	The changes in the AOCI balances, including amounts reclassified from AOCI into net income, are presented in the table below. Foreign currency translation Unrealized (losses) gains on hedging instruments Unrecognized (losses) gains and prior service cost, net Total accumulated other comprehensive loss (in millions) Balance at December 31, 2018 $ (136 ) $ (10 ) $ (579 ) $ (725 ) Other comprehensive income (loss) before reclassifications, net of tax 23 (5 ) — 18 Amounts reclassified from AOCI, net of tax — (1 ) 7 6 Net current period other comprehensive income (loss) 23 (6 ) 7 24 Balance at March 29, 2019 $ (113 ) $ (16 ) $ (572 ) $ (701 ) Balance at December 31, 2017 $ (54 ) $ 9 $ (646 ) $ (691 ) Other comprehensive income before reclassifications, net of tax 33 — — 33 Amounts reclassified from AOCI, net of tax — (1 ) 14 13 Net current period other comprehensive income (loss) 33 (1 ) 14 46 Balance at March 30, 2018 $ (21 ) $ 8 $ (632 ) $ (645 )
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. ASU 2017-12 did not have an impact in the Company's presentation of the earnings effect of hedging instruments in the income statement. Amount Reclassified from AOCI (a) Affected Line Item in the Unaudited Condensed Consolidated Statements of Operations First Quarter Ended Details About AOCI Components March 29, March 30, (in millions) Gain on hedging instruments $ 1 $ 1 Cost of sales - Products 1 1 Income from continuing operations before income taxes — — Provision for income taxes $ 1 $ 1 Income from continuing operations Amortization of defined benefit pension and postretirement items: Net loss (b) $ (9 ) $ (18 ) Income from continuing operations before income taxes 2 4 Provision for income taxes $ (7 ) $ (14 ) Income from continuing operations Total reclassification for the period $ (6 ) $ (13 ) 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 19 for additional information).

L3's Earnings Per Share (Tables

L3's Earnings Per Share (Tables)	3 Months Ended
	Mar. 29, 2019
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. First Quarter Ended March 29, March 30, (in millions, except per share data) Reconciliation of net income: Net income $ 223 $ 208 Net income from continuing operations attributable to noncontrolling interests (6 ) (5 ) Net income attributable to L3’s common shareholders $ 217 $ 203 Earnings attributable to L3’s common shareholders: Continuing operations $ 217 $ 187 Discontinued operations, net of income tax — 16 Net income attributable to L3’s common shareholders $ 217 $ 203 Earnings per share attributable to L3’s common shareholders: Basic: Weighted average common shares outstanding 79.2 78.2 Basic earnings per share: Continuing operations $ 2.74 $ 2.40 Discontinued operations, net of income tax — 0.20 Net income $ 2.74 $ 2.60 Diluted: Common and potential common shares: Weighted average common shares outstanding 79.2 78.2 Effect of dilutive securities 0.8 1.7 Common and potential common shares 80.0 79.9 Diluted earnings per share: Continuing operations $ 2.71 $ 2.34 Discontinued operations, net of income tax — 0.20 Net income $ 2.71 $ 2.54

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 29, 2019
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. March 29, 2019 December 31, 2018 Description Level 1 (1) Level 2 (2) Level 3 (3) Level 1 (1) Level 2 (2) Level 3 (3) (in millions) Assets Cash equivalents $ 756 $ — $ — $ 660 $ — $ — Derivatives (foreign currency forward contracts) — 3 — — 1 — Total assets $ 756 $ 3 $ — $ 660 $ 1 $ — Liabilities Derivatives (foreign currency forward contracts) $ — $ 9 $ — $ — $ 17 $ — Derivatives (treasury lock contracts) (4) — 16 — — — — Contingent consideration — — 16 — — 20 Total liabilities $ — $ 25 $ 16 $ — $ 17 $ 20 __________________ (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, interest rates and consideration of non-performance risk. (3) Level 3 is based on pricing inputs that are not observable and not corroborated by market data. (4) See Note 16 for information regarding the treasury lock contracts.
Changes to Contingent Consideration Obligations	The table below presents the changes to contingent consideration obligations during the quarterly period ended March 29, 2019 . March 29, 2019 (in millions) Balance at beginning of period $ 20 Changes in fair value of contingent consideration, net (4 ) Balance at end of period $ 16

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Mar. 29, 2019
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. March 29, 2019 December 31, 2018 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value (in millions) Senior notes (1) $ 3,322 $ 3,451 $ 3,321 $ 3,355 Foreign currency forward contracts (2) $ (6 ) $ (6 ) $ (16 ) $ (16 ) Treasury lock contracts (3) $ (16 ) $ (16 ) $ — $ — __________________ (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 16 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts. (3) The Company measures the fair values of treasury lock contracts based on 10-year treasury rates. See Note 16 for additional disclosures regarding the notional amounts and fair values of treasury lock contracts.

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 29, 2019
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 March 29, 2019 . Currency Notional Amounts (in millions) U.S. dollar $ 197 Canadian dollar 85 Euro 75 British pound 11 United Arab Emirates dirham 9 New Zealand dollar 9 Total $ 386
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. March 29, 2019 December 31, 2018 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) $ 2 $ 1 $ 7 $ 2 $ 1 $ — $ 13 $ 4 Treasury lock contracts (1) — — — 16 — — — — Total derivative instruments $ 2 $ 1 $ 7 $ 18 $ 1 $ — $ 13 $ 4 __________________ (1) See Note 14 for a description of the fair value hierarchy related to the Company’s foreign currency forward contracts and treasury lock contracts.

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 29, 2019
Leases [Abstract]
Components of Lease Expenses	The components of the Company's lease expense are presented in the table below. First Quarter Ended March 29, 2019 (in millions) Operating lease cost $ 29 Short-term and equipment lease cost 1 Variable lease cost 4 Sublease income (1 ) Net lease cost $ 33 Supplemental operating lease balance sheet information is presented in the table below. March 29, 2019 (in millions) Operating lease right-of-use assets $ 618 Other current liabilities $ 74 Operating lease liabilities 569 Total operating lease liabilities $ 643 Other supplemental information related to the Company's leases is presented in the table below. First Quarter Ended (in millions, except lease term and discount rate) March 29, 2019 Cash paid for amounts included in the measurement of operating lease liabilities $ 33 Right-of-use assets obtained in exchange for new operating lease liabilities $ 3 Weighted average remaining lease term - operating leases (in years) 10.9 Weighted average discount rate - operating leases 4.4 %
Operating Lease, Future Minimum Lease Payments	The following table presents future lease payments under non-cancelable leases as of March 29, 2019 . Operating Leases March 29, 2019 (in millions) 2019 $ 76 2020 91 2021 81 2022 73 2023 64 Thereafter 437 Total future lease payments required 822 Less: imputed interest 179 Total $ 643
Future Minimum Lease Payments under ASC 840	As discussed in Note 2 , the Company has adopted ASC 842 using the optional transition method presenting prior period amounts and disclosures under ASC 840. The following presents the Company's future minimum lease payments for operating leases under ASC 840 at December 31, 2018. Operating Leases December 31, 2018 (in millions) 2019 $ 115 2020 134 2021 82 2022 73 2023 65 Thereafter 506 Total minimum payments required 975 Sublease rentals under non-cancelable leases (7 ) Net minimum payments required $ 968

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits (Tables)	3 Months Ended
	Mar. 29, 2019
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 First Quarter Ended First Quarter Ended March 29, March 30, March 29, March 30, (in millions) Components of net periodic benefit cost: Service cost $ 6 $ 26 $ 1 $ — Interest cost 40 36 1 1 Expected return on plan assets (49 ) (56 ) (1 ) (1 ) Amortization of prior service credits (1 ) — — — Amortization of net loss (gains) 11 19 (1 ) (1 ) Curtailment loss (1) 2 — — — Net periodic benefit cost $ 9 $ 25 $ — $ (1 ) __________________ (1) During the quarterly period ended March 29, 2019, the Company recognized a $2 million pension curtailment loss related to severance and restructuring activities in the C&NS segment.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 29, 2019
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	First Quarter Ended March 29, March 30, (in millions) Interest paid $ 18 $ 37 Income tax payments $ 20 $ 21 Income tax refunds $ 5 $ 2

Segment Information and Disag_2

Segment Information and Disaggregation of Net Sales (Tables)	3 Months Ended
	Mar. 29, 2019
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. First Quarter Ended March 29, March 30, (in millions) Net Sales: ISRS $ 1,259 $ 1,018 C&NS 793 713 Electronic Systems 670 659 Elimination of intercompany sales (22 ) (19 ) Consolidated total $ 2,700 $ 2,371 Operating Income: ISRS $ 130 $ 93 C&NS 84 64 Electronic Systems 97 94 Segment total 311 251 Merger, acquisition and divestiture related expenses and losses (18 ) — Consolidated total $ 293 $ 251 Depreciation and amortization: ISRS $ 23 $ 21 C&NS 16 17 Electronic Systems 19 18 Consolidated total $ 58 $ 56 March 29, December 31, (in millions) Total Assets: ISRS $ 4,823 $ 4,749 C&NS 3,991 3,641 Electronic Systems 4,257 4,128 Corporate 1,192 1,000 Consolidated total $ 14,263 $ 13,518
Revenue by End Customer [Member]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	The tables below present total net sales disaggregated by end customer. First Quarter Ended March 29, 2019 End Customer ISRS C&NS Electronic Systems Consolidated L3 (in millions) Total DoD $ 921 $ 593 $ 335 $ 1,849 Other U.S. Government 26 25 28 79 Total U.S. Government 947 618 363 1,928 Foreign governments (1) 254 86 57 397 Commercial — foreign 20 31 160 211 Commercial — domestic 32 50 82 164 Total $ 1,253 $ 785 $ 662 $ 2,700 First Quarter Ended March 30, 2018 End Customer ISRS C&NS Electronic Systems Consolidated L3 (in millions) Total DoD $ 726 $ 516 $ 320 $ 1,562 Other U.S. Government 30 27 36 93 Total U.S. Government 756 543 356 1,655 Foreign governments (1) 205 83 43 331 Commercial — foreign 29 26 162 217 Commercial — domestic 26 55 87 168 Total $ 1,016 $ 707 $ 648 $ 2,371 __________________ (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. First Quarter Ended March 29, 2019 Contract Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Fixed-price (1) $ 908 $ 577 $ 545 $ 2,030 Cost-plus (2) 295 189 107 591 Time-and-material 50 19 10 79 Total sales $ 1,253 $ 785 $ 662 $ 2,700 First Quarter Ended March 30, 2018 Contract Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Fixed-price (1) $ 639 $ 506 $ 547 $ 1,692 Cost-plus (2) 324 179 93 596 Time-and-material 53 22 8 83 Total sales $ 1,016 $ 707 $ 648 $ 2,371 __________________ (1) Includes fixed-price incentive fee type contracts, which contributed approximately 1% and 2% to the Company's total net sales for the quarterly periods ended March 29, 2019 and March 30, 2018 , respectively. (2) Includes cost-plus award and incentive fee type contracts, which contributed approximately 3% and 4% to the Company's total net sales for the quarterly periods ended March 29, 2019 and March 30, 2018 , respectively.
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. First Quarter Ended March 29, 2019 Sales by Deliverable Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Products $ 855 $ 606 $ 471 $ 1,932 Services 398 179 191 768 Total sales $ 1,253 $ 785 $ 662 $ 2,700 First Quarter Ended March 30, 2018 Sales by Deliverable Type ISRS C&NS Electronic Systems Consolidated L3 (in millions) Products $ 655 $ 532 $ 459 $ 1,646 Services 361 175 189 725 Total sales $ 1,016 $ 707 $ 648 $ 2,371
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. First Quarter Ended March 29, 2019 Revenue Recognition Method ISRS C&NS Electronic Systems Consolidated L3 (in millions) Over time (cost-to-cost method) $ 981 $ 647 $ 417 $ 2,045 Point in time 225 115 163 503 Output method 24 5 67 96 Billing method 23 18 15 56 Total sales $ 1,253 $ 785 $ 662 $ 2,700 First Quarter Ended March 30, 2018 Revenue Recognition Method ISRS C&NS Electronic Systems Consolidated L3 (in millions) Over time (cost-to-cost method) $ 807 $ 576 $ 419 $ 1,802 Point in time 157 103 172 432 Output method 16 7 51 74 Billing method 36 21 6 63 Total sales $ 1,016 $ 707 $ 648 $ 2,371

Severance and Restructuring R_2

Severance and Restructuring Related Costs (Tables)	3 Months Ended
	Mar. 29, 2019
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. First Quarter Ended March 29, March 30, (in millions) Reportable Segment ISRS $ 1 $ 1 C&NS 4 5 Electronic Systems 1 2 Consolidated $ 6 $ 8
Schedule of Restructuring Reserve	The table below presents the change to the Company’s severance and restructuring related liability during the quarterly period ended March 29, 2019 . March 29, 2019 (in millions) Balance at beginning of period $ 14 Additional provisions 6 Cash payments (11 ) Balance at end of period $ 9

Condensed Combining Financial_2

Condensed Combining Financial Information of L3 and Its Subsidiaries (Tables)	3 Months Ended
	Mar. 29, 2019
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 March 29, 2019 Current assets: Cash and cash equivalents $ 856 $ 19 $ 309 $ (76 ) $ 1,108 Billed receivables, net 230 268 306 — 804 Contract assets 580 953 202 — 1,735 Inventories 369 268 259 — 896 Prepaid expenses and other current assets 127 180 55 — 362 Total current assets 2,162 1,688 1,131 (76 ) 4,905 Goodwill 2,124 3,007 1,695 — 6,826 Other assets 1,004 954 574 — 2,532 Investment in and amounts due from consolidated subsidiaries 6,049 6,534 — (12,583 ) — Total assets $ 11,339 $ 12,183 $ 3,400 $ (12,659 ) $ 14,263 Current liabilities $ 797 $ 1,036 $ 675 $ (76 ) $ 2,432 Amounts due to consolidated subsidiaries — — 445 (445 ) — Other long-term liabilities 1,169 963 259 — 2,391 Long-term debt 3,322 — — — 3,322 Total liabilities 5,288 1,999 1,379 (521 ) 8,145 L3 shareholders’ equity 6,051 10,184 2,021 (12,205 ) 6,051 Noncontrolling interests — — — 67 67 Total equity 6,051 10,184 2,021 (12,138 ) 6,118 Total liabilities and equity $ 11,339 $ 12,183 $ 3,400 $ (12,659 ) $ 14,263 L3 Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated L3 (in millions) At December 31, 2018 Current assets: Cash and cash equivalents $ 756 $ 21 $ 306 $ (17 ) $ 1,066 Billed receivables, net 291 341 287 — 919 Contract assets 562 833 195 — 1,590 Inventories 378 258 243 — 879 Prepaid expenses and other current assets 127 166 63 — 356 Total current assets 2,114 1,619 1,094 (17 ) 4,810 Goodwill 2,124 3,009 1,675 — 6,808 Other assets 690 765 445 — 1,900 Investment in and amounts due from consolidated subsidiaries 5,931 6,912 — (12,843 ) — Total assets $ 10,859 $ 12,305 $ 3,214 $ (12,860 ) $ 13,518 Current liabilities $ 821 $ 955 $ 688 $ (17 ) $ 2,447 Amounts due to consolidated subsidiaries — — 417 (417 ) — Other long-term liabilities 878 804 161 — 1,843 Long-term debt 3,321 — — — 3,321 Total liabilities 5,020 1,759 1,266 (434 ) 7,611 L3 shareholders’ equity 5,839 10,546 1,948 (12,494 ) 5,839 Noncontrolling interests — — — 68 68 Total equity 5,839 10,546 1,948 (12,426 ) 5,907 Total liabilities and equity $ 10,859 $ 12,305 $ 3,214 $ (12,860 ) $ 13,518
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 March 29, 2019: Total net sales $ 904 $ 1,418 $ 462 $ (84 ) $ 2,700 Total operating costs and expenses (785 ) (1,312 ) (376 ) 84 (2,389 ) Merger, acquisition and divestiture related expenses and losses (18 ) — — — (18 ) Operating income 101 106 86 — 293 Interest expense (37 ) — — — (37 ) Interest and other income, net 3 1 — — 4 Income from continuing operations before income taxes 67 107 86 — 260 Provision for income taxes (10 ) (15 ) (12 ) — (37 ) Equity in net income of consolidated subsidiaries 160 36 — (196 ) — Net income 217 128 74 (196 ) 223 Net income attributable to noncontrolling interests — — — (6 ) (6 ) Net income attributable to L3 $ 217 $ 128 $ 74 $ (202 ) $ 217 Comprehensive income attributable to L3 $ 241 $ 158 $ 101 $ (259 ) $ 241 For the quarter ended March 30, 2018: Total net sales $ 807 $ 1,239 $ 422 $ (97 ) $ 2,371 Total operating costs and expenses (722 ) (1,155 ) (340 ) 97 (2,120 ) Operating income 85 84 82 — 251 Interest expense (41 ) — — — (41 ) Interest and other income, net 5 — 1 — 6 Income from continuing operations before income taxes 49 84 83 — 216 Provision for income taxes (6 ) (9 ) (9 ) — (24 ) Equity in net income of consolidated subsidiaries 144 47 — (191 ) — Income from continuing operations 187 122 74 (191 ) 192 Income from discontinued operations, net of income taxes 16 — — — 16 Net income 203 122 74 (191 ) 208 Net income attributable to noncontrolling interests — — — (5 ) (5 ) Net income attributable to L3 $ 203 $ 122 $ 74 $ (196 ) $ 203 Comprehensive income attributable to L3 $ 249 $ 153 $ 107 $ (260 ) $ 249
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 quarter ended March 29, 2019: Operating activities: Net cash from operating activities from continuing operations $ 101 $ 55 $ 18 $ — $ 174 Investing activities: Proceeds from sale of businesses, net of closing date cash balances 1 — — — 1 Other investing activities (42 ) (19 ) (14 ) — (75 ) Net cash used in investing activities from continuing operations (41 ) (19 ) (14 ) — (74 ) Financing activities: Dividends paid (70 ) — — — (70 ) Other financing activities 91 (38 ) (4 ) (59 ) (10 ) Net cash from (used in) financing activities from continuing operations 21 (38 ) (4 ) (59 ) (80 ) Effect of foreign currency exchange rate changes on cash — — 3 — 3 Net increase in cash and cash equivalents of discontinued operations 19 — — — 19 Net increase (decrease) in cash 100 (2 ) 3 (59 ) 42 Cash and cash equivalents, beginning of the period 756 21 306 (17 ) 1,066 Cash and cash equivalents, end of the period $ 856 $ 19 $ 309 $ (76 ) $ 1,108 For the quarter ended March 30, 2018: Operating activities: Net cash from (used in) operating activities from continuing operations $ 198 $ (204 ) $ (24 ) $ (5 ) $ (35 ) Investing activities: Other investing activities (62 ) (17 ) (4 ) — (83 ) Net cash used in investing activities from continuing operations (62 ) (17 ) (4 ) — (83 ) Financing activities: Common stock repurchased (119 ) — — — (119 ) Dividends paid (65 ) — — — (65 ) Other financing activities (196 ) 226 (50 ) 58 38 Net cash (used in) from financing activities from continuing operations (380 ) 226 (50 ) 58 (146 ) Effect of foreign currency exchange rate changes on cash — — 6 — 6 Net decrease in cash and cash equivalents of discontinued operations (30 ) — — — (30 ) Net (decrease) increase in cash (274 ) 5 (72 ) 53 (288 ) Cash and cash equivalents, beginning of the period 432 14 287 (71 ) 662 Cash and cash equivalents, end of the period $ 158 $ 19 $ 215 $ (18 ) $ 374

Description of Business (Detail

Description of Business (Details) $ in Millions	Jun. 29, 2018USD ($)	Mar. 29, 2019USD ($)Segment	Oct. 14, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of reportable segments | Segment		3
Gain from discontinued operation	$ 234
Gain from discontinued operation, after tax	177
Payment of working capital adjustment related to disposition of business		$ 20
Ownership percentage after merger (percent)			46.00%
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
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	42
Gain on sale of businesses, after tax	$ 19
Harris Corporation [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ratio of Harris shares received for every L3 common share			1.30
Harris Corporation [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage after merger (percent)			54.00%

Basis of Presentation - Impact

Basis of Presentation - Impact of Adoption of New Accounting Pronouncement (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Assets	$ 14,263			$ 13,518
Liabilities	8,145			$ 7,611
Performance obligations satisfied in prior periods	83
Operating income	$ 293	$ 251
Diluted earnings per share (in dollars per share)	$ 2.71	$ 2.54
Research and development expense	$ 71	$ 75
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Assets			$ 640
Liabilities			$ 640
Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income	$ 66	$ 50
Diluted earnings per share (in dollars per share)	$ 0.63	$ 0.48

Basis of Presentation - Remaini

Basis of Presentation - Remaining Performance Obligations (Details) $ in Billions	Mar. 29, 2019USD ($)
Accounting Policies [Abstract]
Remaining performance obligations	$ 12
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-09-29
Accounting Policies [Abstract]
Remaining performance obligations	6.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Accounting Policies [Abstract]
Remaining performance obligations	3.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Accounting Policies [Abstract]
Remaining performance obligations	1.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Accounting Policies [Abstract]
Remaining performance obligations	$ 1

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
	Mar. 29, 2019	Mar. 30, 2018
Revenue from Contract with Customer [Abstract]
Over time (cost-to-cost method)	76.00%	76.00%
Point in time	19.00%	18.00%
Output method	3.00%	3.00%
Billing method	2.00%	3.00%
Total	100.00%	100.00%

Acquisitions and Divestitures,

Acquisitions and Divestitures, Unaudited Pro Forma Statements of Operations Data (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 30, 2018USD ($)$ / shares
Business Combinations [Abstract]
Pro forma net sales	$ 2,404
Pro forma income from continuing operations attributable to L3	191
Pro forma net income attributable to L3	$ 207
Pro forma diluted earnings per share from continuing operations (in dollars per share) | $ / shares	$ 2.39
Pro forma diluted earnings per share (in dollars per share) | $ / shares	$ 2.59

Acquisitions, Divestitures an_3

Acquisitions, Divestitures and Discontinued Operations Acquisitions and Divestitures, Investments in Unconsolidated Affiliates (Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - Peak Nano [Member] - USD ($) $ in Millions	Mar. 06, 2019	Feb. 16, 2018
Schedule of Equity Method Investments [Line Items]
Investment in nonconsolidated affiliate (percent)		25.00%
Purchase price	$ 20	$ 20
Conversion of note receivable	$ 5
Additional interest acquired (percent)	10.00%
Warrants to acquire additional interest (percent)	10.00%

Acquisitions and Divestitures_2

Acquisitions and Divestitures, Business Divestitures (Details) - USD ($) $ in Millions	Feb. 05, 2019	Jun. 29, 2018	Mar. 29, 2019	Mar. 30, 2018
Business Acquisition [Line Items]
Net sales			$ 2,700	$ 2,371
Income from continuing operations before income taxes			$ 260	216
L-3 Mobile Vision, Inc. [Member]
Business Acquisition [Line Items]
Proceeds from sale of business	$ 1
Business divestiture loss	$ 2
Crestview & TCS [Member]
Business Acquisition [Line Items]
Business divestiture loss		$ 42
Net sales				33
Income from continuing operations before income taxes				$ 1

Acquisitions and Divestitures_3

Acquisitions and Divestitures, Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Discontinued Operations, Income Statement Disclosures [Abstract]
Income from discontinued operations, net of income taxes	$ 0	$ 16
Vertex Aerospace [Member] | Discontinued Operations [Member]
Discontinued Operations, Income Statement Disclosures [Abstract]
Net Sales		371
Operating costs and expenses		(349)
Operating income from discontinued operations		22
Interest expense allocated to discontinued operations		(1)
Income from discontinued operations before income taxes		21
Income tax expense		(5)
Income from discontinued operations, net of income taxes		$ 16

Contract Assets and Contract _3

Contract Assets and Contract Liabilities - Components of Net Contract Assets (Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract assets	$ 1,735	$ 1,590
Contract liabilities — current	(711)	(669)
Contract liabilities — non-current	(28)	(31)
Net contract assets	996	$ 890
Decrease in contract assets	145
Decrease in contract liability	39
Revenue recognized related to contract liabilities	$ 270

Components of Contract Assets (

Components of Contract Assets (Details) - USD ($) $ in Millions	Mar. 29, 2019	Dec. 31, 2018
Contracts Receivable [Abstract]
Unbilled contract receivables, gross	$ 3,035	$ 2,716
Unliquidated progress payments and advances	(1,300)	(1,126)
Total contract assets	$ 1,735	$ 1,590

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials, components and sub-assemblies	$ 372	$ 351
Work in process	335	330
Finished goods	189	198
Total	896	$ 879
G&A costs included in inventory	35
G&A costs incurred and recorded in inventories	301
G&A costs charged to expense from inventories	$ 295

Goodwill and Identifiable Int_3

Goodwill and Identifiable Intangible Assets - Allocated by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill	$ 6,930	$ 6,912
Accumulated impairment losses	(104)	(104)
Balance	6,808
Business acquisitions	2
Foreign currency translation adjustments	16
Balance	6,826
ISRS [Member]
Goodwill [Line Items]
Goodwill	2,664	2,660
Accumulated impairment losses	(46)	(46)
Balance	2,614
Business acquisitions	0
Foreign currency translation adjustments	4
Balance	2,618
C&NS [Member]
Goodwill [Line Items]
Goodwill	2,009	2,004
Accumulated impairment losses	(15)	(15)
Balance	1,989
Business acquisitions	2
Foreign currency translation adjustments	3
Balance	1,994
Electronic Systems [Member]
Goodwill [Line Items]
Goodwill	2,257	2,248
Accumulated impairment losses	(43)	$ (43)
Balance	2,205
Business acquisitions	0
Foreign currency translation adjustments	9
Balance	$ 2,214

Goodwill and Identifiable Int_4

Goodwill and Identifiable Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018	Dec. 31, 2018
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite-lived intangible assets, gross carrying amount	$ 762		$ 762
Finite-lived intangible assets, accumulated amortization	450		438
Finite-lived intangible assets, net carrying amount	312		324
Amortization expense	12	$ 11
Estimated Amortization Expense for Identifiable Intangible Assets [Abstract]
Estimated amortization expense, 2019	51
Estimated amortization expense, 2020	47
Estimated amortization expense, 2021	42
Estimated amortization expense, 2022	37
Estimated amortization expense, 2023	28
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, gross carrying amount	828		828
Intangible assets, net carrying amount	378		390
IPR&D [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 66		66
Customer Contractual Relationships [Member]
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite lived intangible assets, weighted average amortization period	17 years
Finite-lived intangible assets, gross carrying amount	$ 468		468
Finite-lived intangible assets, accumulated amortization	295		288
Finite-lived intangible assets, net carrying amount	$ 173		180
Technology [Member]
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite lived intangible assets, weighted average amortization period	10 years
Finite-lived intangible assets, gross carrying amount	$ 245		245
Finite-lived intangible assets, accumulated amortization	137		132
Finite-lived intangible assets, net carrying amount	$ 108		113
Other [Member]
Finite-Lived Intangible Assets Subject to Amortization [Abstract]
Finite lived intangible assets, weighted average amortization period	12 years
Finite-lived intangible assets, gross carrying amount	$ 49		49
Finite-lived intangible assets, accumulated amortization	18		18
Finite-lived intangible assets, net carrying amount	$ 31		$ 31

Other Current Liabilities and_3

Other Current Liabilities and Other Liabilities (Details) - USD ($) $ in Millions	Mar. 29, 2019	Dec. 31, 2018
Other Current Liabilities [Abstract]
Operating lease liabilities	$ 74	$ 0
Accrued product warranty costs	61	66
Estimated costs in excess of estimated contract value to complete contracts in process in a loss position	46	40
Accrued interest	36	18
Estimated contingent purchase price payable for acquired businesses and other investments	10	10
Other	137	154
Total other current liabilities	364	288
Other Liabilities [Abstract]
Non-current income taxes payable	159	161
Deferred compensation	54	53
Contract liabilities	28	31
Notes payable and capital lease obligations	24	22
Accrued product warranty costs	21	22
Accrued workers' compensation	21	20
Estimated contingent purchase price payable for acquired businesses	6	10
Other	102	117
Total other liabilities	$ 415	$ 436

Other Current Liabilities and_4

Other Current Liabilities and Other Liabilities - Changes in Company's Accrued Product Warranty Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Accrued product warranty costs [Roll Forward]:
Balance at January 1	$ 88	$ 99
Accruals for product warranties issued during the period	14	14
Changes to accruals for product warranties existing before January 1	(1)	1
Settlements made during the period	(19)	(14)
Balance at end of period	$ 82	$ 100

Debt (Details)

Debt (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018	Jan. 31, 2019	Dec. 31, 2018
Long-term debt, current and noncurrent [Abstract]
Proceeds under the credit facility	$ 0	$ 207
Repayments under the credit facility	$ 0	$ 207
Redemption price of senior notes as percentage of principal amount redeemed (percent)	101.00%
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	(21)			(22)
Carrying amount of long-term debt	3,322			3,321
Subsidiaries [Member] | Revolving Credit Facility [Member]
Long-term debt, current and noncurrent [Abstract]
Proceeds under the credit facility	0
Repayments under the credit facility	0
Available borrowings under credit facility	1,000
Senior Notes [Member] | Subsidiaries [Member] | 4.95% Senior Notes due 2021 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt	$ 650		$ 650	650
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes	4.95%
Debt instrument maturity period	2021
Senior Notes [Member] | Subsidiaries [Member] | 3.85% Senior Notes due 2023 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt	$ 800			800
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes	3.85%
Debt instrument maturity period	2023
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	2024
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	2026
Senior Notes [Member] | Subsidiaries [Member] | 4.40% Senior Notes due 2028 [Member]
Components of Debt [Abstract]
Principal amount of long-term debt	$ 1,000			$ 1,000
Long-term debt, current and noncurrent [Abstract]
Interest rate on senior notes	4.40%
Debt instrument maturity period	2028

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	14.20%	11.10%
Anticipated decrease in unrecognized tax benefits over the next 12 months	$ 30
Accrued potential interest included within current and non-current income taxes payable	15		$ 15
Accrued potential interest included within current and non-current income taxes payable, after income taxes	11		11
Potential penalties	$ 8		$ 9

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	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	$ 5,839
Other comprehensive income (loss) before reclassifications, net of tax	18	$ 33
Amounts reclassified from AOCI, net of tax	6	13
Net current period other comprehensive (loss) income	24	46
Ending Balance	6,051
Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(725)	(691)
Ending Balance	(701)	(645)
Foreign Currency Translation [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(136)	(54)
Other comprehensive income (loss) before reclassifications, net of tax	23	33
Amounts reclassified from AOCI, net of tax	0	0
Net current period other comprehensive (loss) income	23	33
Ending Balance	(113)	(21)
Unrealized Gains (Losses) on Hedging Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(10)	9
Other comprehensive income (loss) before reclassifications, net of tax	(5)	0
Amounts reclassified from AOCI, net of tax	(1)	(1)
Net current period other comprehensive (loss) income	(6)	(1)
Ending Balance	(16)	8
Unrecognized (Losses) Gains and Prior Service Cost, Net [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(579)	(646)
Other comprehensive income (loss) before reclassifications, net of tax	0	0
Amounts reclassified from AOCI, net of tax	7	14
Net current period other comprehensive (loss) income	7	14
Ending Balance	$ (572)	$ (632)

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
	Mar. 29, 2019	Mar. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations before income taxes	$ 260	$ 216
Provision for income taxes	(37)	(24)
Income from continuing operations	223	192
Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations	(6)	(13)
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	1	1
Provision for income taxes	0	0
Income from continuing operations	1	1
Amortization of Defined Benefit Pension and Postretirement Items [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	2	4
Income from continuing operations	(7)	(14)
Net loss	(9)	(18)
Product [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of Goods and services sold	(1,442)	(1,191)
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	$ 1	$ 1

Equity (Details)

Equity (Details) - USD ($)	Jul. 10, 2018	Mar. 29, 2019	Mar. 30, 2018	May 08, 2017
Class of Stock [Line Items]
Cash dividends declared per common share (in dollars per share)	$ 0.85	$ 0.85	$ 0.8
Cash dividends		$ 70,000,000
Accrued dividends through payment		$ 3,000,000
Share Repurchase Program May 8, 2017 [Member]
Class of Stock [Line Items]
Amount of shares authorized to be repurchased				$ 1,500,000,000

L3's Earnings Per Share (Detail

L3's Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Reconciliation of net income:
Net income	$ 223	$ 208
Net income from continuing operations attributable to noncontrolling interests	(6)	(5)
Net income attributable to L3	217	203
Earnings attributable to L3’s common shareholders:
Continuing operations	217	187
Discontinued operations, net of income tax	0	16
Net income attributable to L3	$ 217	$ 203
Basic:
Weighted average common shares outstanding (in shares)	79.2	78.2
Basic earnings per share:
Continuing operations (in dollars per share)	$ 2.74	$ 2.40
Discontinued operations (in dollars per share)	0	0.20
Basic earnings per share (in dollars per share)	$ 2.74	$ 2.60
Common and potential common shares [Abstract]
Weighted average common shares outstanding (in shares)	79.2	78.2
Effect of dilutive securities (in shares)	0.8	1.7
Common and potential common shares (in shares)	80	79.9
Diluted earnings per share:
Continuing operations (in dollars per share)	$ 2.71	$ 2.34
Discontinued operations, net of income tax (in dollars per share)	0	0.20
Diluted earnings per share (in dollars per share)	$ 2.71	$ 2.54
Shares excluded from computation of diluted earnings per share (in shares)	0.5	0.3

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 29, 2019	Dec. 31, 2018
Liabilities [Abstract]
Contingent consideration	$ 20	$ 16	$ 20
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	20
Changes in fair value of contingent consideration, net	(4)
Balance at end of period	16
Recurring [Member] | Level 1 [Member]
Assets [Abstract]
Cash equivalents		756	660
Derivatives (foreign currency forward contracts)		0	0
Total assets		756	660
Liabilities [Abstract]
Derivatives (foreign currency forward contracts)		0	0
Derivatives (treasury lock contracts)(4)		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)		3	1
Total assets		3	1
Liabilities [Abstract]
Derivatives (foreign currency forward contracts)		9	17
Derivatives (treasury lock contracts)(4)		16	0
Contingent consideration	0	0	0
Total liabilities		25	17
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
Derivatives (treasury lock contracts)(4)		0	0
Contingent consideration	20	16	20
Total liabilities		$ 16	$ 20
Business Combination, Contingent Consideration, Liability [Abstract]
Balance at beginning of period	20
Balance at end of period	$ 16

Financial Instruments (Details)

Financial Instruments (Details) - USD ($) $ in Millions	Mar. 29, 2019	Dec. 31, 2018
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes	$ 3,322	$ 3,321
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes	3,451	3,355
Foreign Currency Forward Contracts [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign currency forward contracts	(6)	(16)
Foreign Currency Forward Contracts [Member] | Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign currency forward contracts	(6)	(16)
Treasury Lock Contracts [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign currency forward contracts	(16)	0
Treasury Lock Contracts [Member] | Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign currency forward contracts	$ (16)	$ 0

Derivative Financial Instrume_3

Derivative Financial Instruments, Outstanding Forward Contracts by Currency (Details) - Foreign Currency Forward Contracts [Member] $ in Millions	Mar. 29, 2019USD ($)
Derivative [Line Items]
Notional amounts	$ 386
U.S. dollar
Derivative [Line Items]
Notional amounts	197
Canadian dollar
Derivative [Line Items]
Notional amounts	85
Euro
Derivative [Line Items]
Notional amounts	75
British pound
Derivative [Line Items]
Notional amounts	11
United Arab Emirates dirham
Derivative [Line Items]
Notional amounts	9
New Zealand dollar
Derivative [Line Items]
Notional amounts	$ 9

Derivative Financial Instrume_4

Derivative Financial Instruments, Fair Value on Consolidated Balance Sheet (Details) $ in Millions	3 Months Ended
	Mar. 29, 2019USD ($)	Mar. 30, 2018USD ($)	Jan. 31, 2019USD ($)treasury_lock_contract	Dec. 31, 2018USD ($)
Derivatives, Fair Value [Line Items]
Pre-tax gain on foreign currency forward contracts	$ 1	$ 1
Estimated net amount of existing gains expected to be reclassified into income within the next 12 months	5
Deferred hedging losses, net of tax	12
Foreign Currency Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional amounts	386
Treasury Lock Contracts [Member]
Derivatives, Fair Value [Line Items]
Number of derivative instruments held | treasury_lock_contract			2
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	2			$ 1
Other Current Assets [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	2			1
Other Current Assets [Member] | Treasury Lock Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	0			0
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	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			0
Other Assets [Member] | Treasury Lock Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	0			0
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	7			13
Other Current Liabilities [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	7			13
Other Current Liabilities [Member] | Treasury Lock Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	0			0
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	18			4
Other Liabilities [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	2			4
Other Liabilities [Member] | Treasury Lock Contracts [Member] | Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	16			0
Subsidiaries [Member]
Derivatives, Fair Value [Line Items]
Principal amount of long-term debt	3,350			3,350
Subsidiaries [Member] | Senior Notes [Member] | 4.95% Senior Notes due 2021 [Member]
Derivatives, Fair Value [Line Items]
Principal amount of long-term debt	$ 650		$ 650	$ 650

Leases (Details)

Leases (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 29, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 29
Short-term and equipment lease cost	1
Variable lease cost	4
Sublease income	(1)
Net lease cost	33
Operating lease right-of-use assets	618	$ 0
Other current liabilities	74	0
Operating lease liabilities	569	0
Total operating lease liabilities	643
Amount of leases set to commence between 2019 and 2020	$ 115
Rent expense		105
Sublease rental income		$ 2
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lease term of leases commencing between 2019 and 2020	10 years
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lease term of leases commencing between 2019 and 2020	15 years

Leases - Other Information (Det

Leases - Other Information (Details) $ in Millions	3 Months Ended
	Mar. 29, 2019USD ($)
Leases [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 33
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 3
Weighted average remaining lease term - operating leases (in years)	10 years 10 months 24 days
Weighted average discount rate - operating leases (percent)	4.40%

Leases - Future Minimum Lease P

Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Mar. 29, 2019	Dec. 31, 2018
Operating Leases
2019	$ 76
2020	91
2021	81
2022	73
2023	64
Thereafter	437
Total future lease payments required	822
Less: imputed interest	179
Total	$ 643
Minimum Lease Payments Due, under ASC 840
2019		$ 115
2020		134
2021		82
2022		73
2023		65
Thereafter		506
Total minimum payments required		975
Sublease rentals under non-cancelable leases		(7)
Net minimum payments required		$ 968

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
	Mar. 29, 2019	Mar. 30, 2018
Pension Plans [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 6	$ 26
Interest cost	40	36
Expected return on plan assets	(49)	(56)
Amortization of prior service credits	(1)	0
Amortization of net loss (gains)	11	19
Curtailment loss	2	0
Net periodic benefit cost	9	25
Postretirement Benefit Plans [Member]
Components of net periodic benefit cost [Abstract]
Service cost	1	0
Interest cost	1	1
Expected return on plan assets	(1)	(1)
Amortization of prior service credits	0	0
Amortization of net loss (gains)	(1)	(1)
Curtailment loss	0	0
Net periodic benefit cost	0	$ (1)
C&NS [Member] | Pension Plans [Member]
Components of net periodic benefit cost [Abstract]
Curtailment loss	$ 2

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits, Contributions (Details) $ in Millions	3 Months Ended
	Mar. 29, 2019USD ($)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit plans	$ 8
Expected contributions to plans during the remainder of fiscal year	72
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit plans	1
Expected contributions to plans during the remainder of fiscal year	$ 7

Stock-Based Compensation, Restr

Stock-Based Compensation, Restricted Stock Units (Details) - Unvested Restricted Stock Awards [Member]	3 Months Ended
	Mar. 29, 2019$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in shares) | shares	272,703
Weighted average grant date fair value (in dollars per share) | $ / shares	$ 206.59
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

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Interest paid	$ 18	$ 37
Income tax payments	20	21
Income tax refunds	$ 5	$ 2

Segment Information and Disag_3

Segment Information and Disaggregation of Net Sales (Details) $ in Millions	3 Months Ended
	Mar. 29, 2019USD ($)Segment	Mar. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	3
Net Sales [Abstract]
Net sales	$ 2,700	$ 2,371
Operating Income [Abstract]
Merger, acquisition and divestiture related expenses and losses	(18)	0
Operating income	293	251
Depreciation and amortization [Abstract]
Depreciation and amortization	58	56
Total Assets:
Total assets	14,263		$ 13,518
ISRS [Member]
Net Sales [Abstract]
Net sales	1,253	1,016
C&NS [Member]
Net Sales [Abstract]
Net sales	785	707
Electronic Systems [Member]
Net Sales [Abstract]
Net sales	662	648
Operating Segments [Member]
Operating Income [Abstract]
Operating income	311	251
Operating Segments [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	1,259	1,018
Operating Income [Abstract]
Operating income	130	93
Depreciation and amortization [Abstract]
Depreciation and amortization	23	21
Total Assets:
Total assets	4,823		4,749
Operating Segments [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	793	713
Operating Income [Abstract]
Operating income	84	64
Depreciation and amortization [Abstract]
Depreciation and amortization	16	17
Total Assets:
Total assets	3,991		3,641
Operating Segments [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	670	659
Operating Income [Abstract]
Operating income	97	94
Depreciation and amortization [Abstract]
Depreciation and amortization	19	18
Total Assets:
Total assets	4,257		4,128
Corporate [Member]
Total Assets:
Total assets	1,192		$ 1,000
Elimination of Intercompany Sales [Member]
Net Sales [Abstract]
Net sales	(22)	(19)
Department of Defense [Member]
Net Sales [Abstract]
Net sales	1,849	1,562
Department of Defense [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	921	726
Department of Defense [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	593	516
Department of Defense [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	335	320
Other U.S. Government [Member]
Net Sales [Abstract]
Net sales	79	93
Other U.S. Government [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	26	30
Other U.S. Government [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	25	27
Other U.S. Government [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	28	36
Total U. S. Government [Member]
Net Sales [Abstract]
Net sales	1,928	1,655
Total U. S. Government [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	947	756
Total U. S. Government [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	618	543
Total U. S. Government [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	363	356
Foreign Government Debt [Member]
Net Sales [Abstract]
Net sales	397	331
Foreign Government Debt [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	254	205
Foreign Government Debt [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	86	83
Foreign Government Debt [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	57	43
Commercial - Foreign [Member]
Net Sales [Abstract]
Net sales	211	217
Commercial - Foreign [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	20	29
Commercial - Foreign [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	31	26
Commercial - Foreign [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	160	162
Commercial - Domestic [Member]
Net Sales [Abstract]
Net sales	164	168
Commercial - Domestic [Member] | ISRS [Member]
Net Sales [Abstract]
Net sales	32	26
Commercial - Domestic [Member] | C&NS [Member]
Net Sales [Abstract]
Net sales	50	55
Commercial - Domestic [Member] | Electronic Systems [Member]
Net Sales [Abstract]
Net sales	$ 82	$ 87

Segment Information and Disag_4

Segment Information and Disaggregation of Net Sales - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Disaggregation of Revenue [Line Items]
Direct sales to end customer as percent of consolidated sales (percent)	63.00%	65.00%
Indirect sales as subcontractor or supplier as percent of consolidated sales (percent)	37.00%	35.00%
Fixed price incentive fee type contracts as percent of net sales (percent)	1.00%	2.00%
Cost-plus and incentive fee type contracts as percent of net sales (percent)	3.00%	4.00%
Total sales	$ 2,700	$ 2,371
ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,253	1,016
C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	785	707
Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	662	648
Department of Defense [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,849	1,562
Department of Defense [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	921	726
Department of Defense [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	593	516
Department of Defense [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	335	320
Other U.S. Government [Member]
Disaggregation of Revenue [Line Items]
Total sales	79	93
Other U.S. Government [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	26	30
Other U.S. Government [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	25	27
Other U.S. Government [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	28	36
Total U. S. Government [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,928	1,655
Total U. S. Government [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	947	756
Total U. S. Government [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	618	543
Total U. S. Government [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	363	356
Foreign Government Debt [Member]
Disaggregation of Revenue [Line Items]
Total sales	397	331
Foreign Government Debt [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	254	205
Foreign Government Debt [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	86	83
Foreign Government Debt [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	57	43
Commercial - Foreign [Member]
Disaggregation of Revenue [Line Items]
Total sales	211	217
Commercial - Foreign [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	20	29
Commercial - Foreign [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	31	26
Commercial - Foreign [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	160	162
Commercial - Domestic [Member]
Disaggregation of Revenue [Line Items]
Total sales	164	168
Commercial - Domestic [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	32	26
Commercial - Domestic [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	50	55
Commercial - Domestic [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	82	87
Product [Member]
Disaggregation of Revenue [Line Items]
Total sales	1,932	1,646
Product [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	855	655
Product [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	606	532
Product [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	471	459
Services [Member]
Disaggregation of Revenue [Line Items]
Total sales	768	725
Services [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	398	361
Services [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	179	175
Services [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	191	189
Fixed-price Contract [Member]
Disaggregation of Revenue [Line Items]
Total sales	2,030	1,692
Fixed-price Contract [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	908	639
Fixed-price Contract [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	577	506
Fixed-price Contract [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	545	547
Cost-plus Contract [Member]
Disaggregation of Revenue [Line Items]
Total sales	591	596
Cost-plus Contract [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	295	324
Cost-plus Contract [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	189	179
Cost-plus Contract [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	107	93
Time-and-materials Contract [Member]
Disaggregation of Revenue [Line Items]
Total sales	79	83
Time-and-materials Contract [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	50	53
Time-and-materials Contract [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	19	22
Time-and-materials Contract [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	10	8
Over Time (Cost to Cost Method) [Member]
Disaggregation of Revenue [Line Items]
Total sales	2,045	1,802
Over Time (Cost to Cost Method) [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	981	807
Over Time (Cost to Cost Method) [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	647	576
Over Time (Cost to Cost Method) [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	417	419
Point in Time [Member]
Disaggregation of Revenue [Line Items]
Total sales	503	432
Point in Time [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	225	157
Point in Time [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	115	103
Point in Time [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	163	172
Output Method [Member]
Disaggregation of Revenue [Line Items]
Total sales	96	74
Output Method [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	24	16
Output Method [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	5	7
Output Method [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	67	51
Billing Method [Member]
Disaggregation of Revenue [Line Items]
Total sales	56	63
Billing Method [Member] | ISRS [Member]
Disaggregation of Revenue [Line Items]
Total sales	23	36
Billing Method [Member] | C&NS [Member]
Disaggregation of Revenue [Line Items]
Total sales	18	21
Billing Method [Member] | Electronic Systems [Member]
Disaggregation of Revenue [Line Items]
Total sales	$ 15	$ 6

Severance and Restructuring R_3

Severance and Restructuring Related Costs (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 29, 2019USD ($)Employees	Mar. 30, 2018USD ($)	Dec. 31, 2017USD ($)Employees	Dec. 31, 2018USD ($)
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	$ 6		$ 26
Number of employees of restructuring costs | Employees	300		800
Remaining balance of employee severance and restructuring costs	$ 9			$ 14
ISRS [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	1	$ 1
C&NS [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	4	5
Electronic Systems [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	1	2
Consolidated [Member]
Restructuring Cost and Reserve [Line Items]
Severance and restructuring related costs	$ 6	$ 8

Severance and Restructuring R_4

Severance and Restructuring Related Costs - Restructuring Reserve (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 29, 2019	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Balance at beginning of period	$ 14
Additional provisions	6	$ 26
Cash payments	(11)
Balance at end of period	$ 9

Condensed Combining Financial_3

Condensed Combining Financial Information of L3 and Its Subsidiaries- Condensed Combining Balance Sheets (Details) - USD ($) $ in Millions	Mar. 29, 2019	Dec. 31, 2018	Mar. 30, 2018	Dec. 31, 2017
Current assets [Abstract]
Cash and cash equivalents	$ 1,108	$ 1,066	$ 374	$ 662
Billed receivables, net	804	919
Contract assets	1,735	1,590
Inventories	896	879
Prepaid expenses and other current assets	362	356
Total current assets	4,905	4,810
Goodwill	6,826	6,808
Other assets	2,532	1,900
Investment in and amounts due from consolidated subsidiaries	0	0
Total assets	14,263	13,518
Current liabilities	2,432	2,447
Amounts due to consolidated subsidiaries	0	0
Other long-term liabilities	2,391	1,843
Long-term debt	3,322	3,321
Total liabilities	8,145	7,611
L3 shareholders' equity	6,051	5,839
Noncontrolling interests	67	68
Total equity	6,118	5,907	5,320	5,151
Total liabilities and equity	14,263	13,518
Eliminations [Member]
Current assets [Abstract]
Cash and cash equivalents	(76)	(17)	(18)	(71)
Billed receivables, net	0	0
Contract assets	0	0
Inventories	0	0
Prepaid expenses and other current assets	0	0
Total current assets	(76)	(17)
Goodwill	0	0
Other assets	0	0
Investment in and amounts due from consolidated subsidiaries	(12,583)	(12,843)
Total assets	(12,659)	(12,860)
Current liabilities	(76)	(17)
Amounts due to consolidated subsidiaries	(445)	(417)
Other long-term liabilities	0	0
Long-term debt	0	0
Total liabilities	(521)	(434)
L3 shareholders' equity	(12,205)	(12,494)
Noncontrolling interests	67	68
Total equity	(12,138)	(12,426)
Total liabilities and equity	(12,659)	(12,860)
L-3 [Member]
Current assets [Abstract]
Cash and cash equivalents	856	756	158	432
Billed receivables, net	230	291
Contract assets	580	562
Inventories	369	378
Prepaid expenses and other current assets	127	127
Total current assets	2,162	2,114
Goodwill	2,124	2,124
Other assets	1,004	690
Investment in and amounts due from consolidated subsidiaries	6,049	5,931
Total assets	11,339	10,859
Current liabilities	797	821
Amounts due to consolidated subsidiaries	0	0
Other long-term liabilities	1,169	878
Long-term debt	3,322	3,321
Total liabilities	5,288	5,020
L3 shareholders' equity	6,051	5,839
Noncontrolling interests	0	0
Total equity	6,051	5,839
Total liabilities and equity	11,339	10,859
Guarantor Subsidiaries [Member]
Current assets [Abstract]
Cash and cash equivalents	19	21	19	14
Billed receivables, net	268	341
Contract assets	953	833
Inventories	268	258
Prepaid expenses and other current assets	180	166
Total current assets	1,688	1,619
Goodwill	3,007	3,009
Other assets	954	765
Investment in and amounts due from consolidated subsidiaries	6,534	6,912
Total assets	12,183	12,305
Current liabilities	1,036	955
Amounts due to consolidated subsidiaries	0	0
Other long-term liabilities	963	804
Long-term debt	0	0
Total liabilities	1,999	1,759
L3 shareholders' equity	10,184	10,546
Noncontrolling interests	0	0
Total equity	10,184	10,546
Total liabilities and equity	12,183	12,305
Non-Guarantor Subsidiaries [Member]
Current assets [Abstract]
Cash and cash equivalents	309	306	$ 215	$ 287
Billed receivables, net	306	287
Contract assets	202	195
Inventories	259	243
Prepaid expenses and other current assets	55	63
Total current assets	1,131	1,094
Goodwill	1,695	1,675
Other assets	574	445
Investment in and amounts due from consolidated subsidiaries	0	0
Total assets	3,400	3,214
Current liabilities	675	688
Amounts due to consolidated subsidiaries	445	417
Other long-term liabilities	259	161
Long-term debt	0	0
Total liabilities	1,379	1,266
L3 shareholders' equity	2,021	1,948
Noncontrolling interests	0	0
Total equity	2,021	1,948
Total liabilities and equity	$ 3,400	$ 3,214

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
	Mar. 29, 2019	Mar. 30, 2018
Condensed Financial Statements, Captions [Line Items]
Total sales	$ 2,700	$ 2,371
Total operating costs and expenses	(2,389)	(2,120)
Merger, acquisition and divestiture related expenses and losses	(18)	0
Operating income	293	251
Interest expense	(37)	(41)
Interest and other income, net	4	6
Income from continuing operations before income taxes	260	216
Provision (benefit) for income taxes	(37)	(24)
Equity in net loss of consolidated subsidiaries	0	0
Income from continuing operations	223	192
Loss from discontinued operations, net of income taxes	0	16
Net income	223	208
Net income attributable to noncontrolling interests	(6)	(5)
Net income attributable to L3	217	203
Comprehensive income attributable to L3	241	249
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	(84)	(97)
Total operating costs and expenses	84	97
Merger, acquisition and divestiture related expenses and losses	0
Operating income	0	0
Interest expense	0	0
Interest and other income, net	0	0
Income from continuing operations before income taxes	0	0
Provision (benefit) for income taxes	0	0
Equity in net loss of consolidated subsidiaries	(196)	(191)
Income from continuing operations		(191)
Loss from discontinued operations, net of income taxes		0
Net income	(196)	(191)
Net income attributable to noncontrolling interests	(6)	(5)
Net income attributable to L3	(202)	(196)
Comprehensive income attributable to L3	(259)	(260)
L-3 [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	904	807
Total operating costs and expenses	(785)	(722)
Merger, acquisition and divestiture related expenses and losses	(18)
Operating income	101	85
Interest expense	(37)	(41)
Interest and other income, net	3	5
Income from continuing operations before income taxes	67	49
Provision (benefit) for income taxes	(10)	(6)
Equity in net loss of consolidated subsidiaries	160	144
Income from continuing operations		187
Loss from discontinued operations, net of income taxes		16
Net income	217	203
Net income attributable to noncontrolling interests	0	0
Net income attributable to L3	217	203
Comprehensive income attributable to L3	241	249
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	1,418	1,239
Total operating costs and expenses	(1,312)	(1,155)
Merger, acquisition and divestiture related expenses and losses	0
Operating income	106	84
Interest expense	0	0
Interest and other income, net	1	0
Income from continuing operations before income taxes	107	84
Provision (benefit) for income taxes	(15)	(9)
Equity in net loss of consolidated subsidiaries	36	47
Income from continuing operations		122
Loss from discontinued operations, net of income taxes		0
Net income	128	122
Net income attributable to noncontrolling interests	0	0
Net income attributable to L3	128	122
Comprehensive income attributable to L3	158	153
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total sales	462	422
Total operating costs and expenses	(376)	(340)
Merger, acquisition and divestiture related expenses and losses	0
Operating income	86	82
Interest expense	0	0
Interest and other income, net	0	1
Income from continuing operations before income taxes	86	83
Provision (benefit) for income taxes	(12)	(9)
Equity in net loss of consolidated subsidiaries	0	0
Income from continuing operations		74
Loss from discontinued operations, net of income taxes		0
Net income	74	74
Net income attributable to noncontrolling interests	0	0
Net income attributable to L3	74	74
Comprehensive income attributable to L3	$ 101	$ 107

Condensed Combining Financial_5

Condensed Combining Financial Information of L3 and Its Subsidiaries- Condensed Combining Statements of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Operating activities [Abstract]
Net cash from operating activities from continuing operations	$ 174	$ (35)
Investing activities [Abstract]
Proceeds from sale of businesses, net of closing date cash balances	1	0
Other investing activities	(75)	(83)
Net cash used in investing activities from continuing operations	(74)	(83)
Financing activities [Abstract]
Common stock repurchased	0	(119)
Dividends paid	(70)	(65)
Other financing activities	(10)	38
Net cash used in financing activities from continuing operations	(80)	(146)
Effect of foreign currency exchange rate changes on cash	3	6
Net decrease in cash and cash equivalents of discontinued operations	19	(30)
Net (decrease) increase in cash	42	(288)
Cash and cash equivalents, beginning of the period	1,066	662
Cash and cash equivalents, end of the period	1,108	374
Eliminations [Member]
Operating activities [Abstract]
Net cash from operating activities from continuing operations	0	(5)
Investing activities [Abstract]
Proceeds from sale of businesses, net of closing date cash balances	0
Other investing activities	0	0
Net cash used in investing activities from continuing operations	0	0
Financing activities [Abstract]
Common stock repurchased		0
Dividends paid	0	0
Other financing activities	(59)	58
Net cash used in financing activities from continuing operations	(59)	58
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	(59)	53
Cash and cash equivalents, beginning of the period	(17)	(71)
Cash and cash equivalents, end of the period	(76)	(18)
L-3 [Member]
Operating activities [Abstract]
Net cash from operating activities from continuing operations	101	198
Investing activities [Abstract]
Proceeds from sale of businesses, net of closing date cash balances	1
Other investing activities	(42)	(62)
Net cash used in investing activities from continuing operations	(41)	(62)
Financing activities [Abstract]
Common stock repurchased		(119)
Dividends paid	(70)	(65)
Other financing activities	91	(196)
Net cash used in financing activities from continuing operations	21	(380)
Effect of foreign currency exchange rate changes on cash	0	0
Net decrease in cash and cash equivalents of discontinued operations	19	(30)
Net (decrease) increase in cash	100	(274)
Cash and cash equivalents, beginning of the period	756	432
Cash and cash equivalents, end of the period	856	158
Guarantor Subsidiaries [Member]
Operating activities [Abstract]
Net cash from operating activities from continuing operations	55	(204)
Investing activities [Abstract]
Proceeds from sale of businesses, net of closing date cash balances	0
Other investing activities	(19)	(17)
Net cash used in investing activities from continuing operations	(19)	(17)
Financing activities [Abstract]
Common stock repurchased		0
Dividends paid	0	0
Other financing activities	(38)	226
Net cash used in financing activities from continuing operations	(38)	226
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	(2)	5
Cash and cash equivalents, beginning of the period	21	14
Cash and cash equivalents, end of the period	19	19
Non-Guarantor Subsidiaries [Member]
Operating activities [Abstract]
Net cash from operating activities from continuing operations	18	(24)
Investing activities [Abstract]
Proceeds from sale of businesses, net of closing date cash balances	0
Other investing activities	(14)	(4)
Net cash used in investing activities from continuing operations	(14)	(4)
Financing activities [Abstract]
Common stock repurchased		0
Dividends paid	0	0
Other financing activities	(4)	(50)
Net cash used in financing activities from continuing operations	(4)	(50)
Effect of foreign currency exchange rate changes on cash	3	6
Net decrease in cash and cash equivalents of discontinued operations	0	0
Net (decrease) increase in cash	3	(72)
Cash and cash equivalents, beginning of the period	306	287
Cash and cash equivalents, end of the period	$ 309	$ 215

Uncategorized Items - lll-20190

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 13,000,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 13,000,000