Acquisitions and Divestitures, Unaudited Pro Forma Statements of Operations Data (Details) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 30, 2018 USD ($) $ / 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

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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-Name Accounting Standards Codification
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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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