Divestitures and Acquisitions - Unaudited Pro Forma Statements of Operations Data (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 25, 2016	Mar. 27, 2015
Business Combinations [Abstract]
Pro forma net sales	$ 2,353	$ 2,518
Pro forma income from continuing operations	167	108
Pro forma net income attributable to L-3	$ 227	$ 108
Pro forma diluted earnings per share from continuing operations	$ 2.08	$ 1.24
Pro forma diluted earnings per share	$ 2.87	$ 1.29

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

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- Definition

The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect, for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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- Definition

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.

+ References

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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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- References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph b
-Subparagraph 7
-Article 11

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