Acquisitions, Divestitures and Discontinued Operations, Unaudited Pro Forma Statements of Operations Data (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Pro forma net sales	$ 10,324	$ 9,741
Pro forma income from continuing operations attributable to L3	805	756
Pro forma net income attributable to L3	$ 1,010	$ 680
Pro forma diluted earnings per share from continuing operations (in dollars per share)	$ 10.11	$ 9.50
Pro forma diluted earnings per share (in dollars per share)	$ 12.69	$ 8.54

The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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Amount after tax of pro forma income from continuing operations as if the business combination had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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Pro forma diluted earnings per share, which is commonly presented in initial public offerings.

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