Business Combination, Acquisition-related Costs, After Tax

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Gain (Loss) on Disposition of Business, After Tax

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period from effect of Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete.

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Tax Cuts And Jobs Act Of 2017 Incomplete Accounting Provisional Income Tax Expense Benefit

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The difference between the reacquisition price and the net carrying amount of the extinguished debt recognized currently as a component of income in the period of extinguishment, net of tax.

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Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount after tax of income (loss) from continuing operations including portion attributable to the noncontrolling interest.

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The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended								12 Months Ended
	Jun. 29, 2018	Dec. 31, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Line Items]
Sales		$ 2,771	$ 2,519	$ 2,583	$ 2,371	$ 2,574	$ 2,293	$ 2,385	$ 2,321	$ 10,244	$ 9,573	$ 9,210
Operating income		276	272	321	251	268	232	294	237	1,120	1,031	958
Income from continuing operations		232	208	189	192	271	146	195	157	821	769	633
Net income		231	208	379	208	293	25	207	168	1,026	693	724
Net income attributable to L3		$ 225	$ 202	$ 375	$ 203	$ 289	$ 22	$ 202	$ 164	$ 1,005	$ 677	$ 710
Basic EPS from continuing operations (in dollars per share)		$ 2.87	$ 2.57	$ 2.36	$ 2.40	$ 3.42	$ 1.83	$ 2.44	$ 1.97	$ 10.19	$ 9.65	$ 7.99
Basic EPS (in dollars per share)		2.86	2.57	4.78	2.60	3.70	0.28	2.59	2.11	12.80	8.68	9.17
Diluted EPS from continuing operations (in dollars per share)		2.83	2.54	2.33	2.34	3.34	1.79	2.39	1.93	10.05	9.46	7.86
Earnings Per Share, Diluted		$ 2.82	$ 2.54	$ 4.72	$ 2.54	$ 3.62	0.28	$ 2.54	$ 2.07	$ 12.63	$ 8.51	$ 9.01
Debt retirement charge			$ 21	$ 48						$ (69)	$ 0	$ (7)
Debt retirement charge, after tax			16	$ 36
Gain on sale of businesses										42	0	0
Acquisition and merger related costs		$ 23	5
Acquisition and merger related costs, after tax		$ 19	$ 4
Estimated tax benefit amount						$ 79
Earnings per share, diluted (in dollars per share)						$ 0.99
Crestview Aerospace and TCS [Member]
Quarterly Financial Data [Line Items]
Sales										64	119	166
Earnings Per Share, Diluted		$ 0.03	$ 0.04	$ 0.31
Gain on sale of businesses	$ 42	$ 2	$ 4	$ 48						42	0	0
Gain on sale of businesses, after tax	$ 19	$ 2	$ 4	$ 25
Vertex Aerospace [Member]
Quarterly Financial Data [Line Items]
Sales										$ 600	1,400	$ 1,300
Earnings Per Share, Diluted				$ 2.27			$ 1.67
Gain on sale of businesses				$ 237
Gain on sale of businesses, after tax				$ 180
Goodwill impairment charges							$ 187				$ 187
Debt Retirement Charges [Member]
Quarterly Financial Data [Line Items]
Earnings Per Share, Diluted			$ 0.21	$ 0.45
Merger and Acquisition Related Costs [Member]
Quarterly Financial Data [Line Items]
Earnings Per Share, Diluted		$ 0.24	$ 0.06