Acquisitions - Unaudited Pro Forma Statements of Operations Data (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 26, 2014	Sep. 27, 2013	Sep. 26, 2014	Sep. 27, 2013
Business Combinations [Abstract]
Pro forma net sales	$ 2,940	$ 3,025	$ 8,923	$ 9,450
Pro forma net income attributable to L-3	$ 154	$ 200	$ 460	$ 567
Pro forma diluted earnings per share	$ 1.78	$ 2.19	$ 5.20	$ 6.21

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=25497992&loc=d3e1392-128463

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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.

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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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