Acquisitions and Divestitures - Unaudited Pro Forma Statements of Operations Data (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 27, 2015	Mar. 28, 2014
Business Combinations [Abstract]
Pro forma net sales	$ 2,715	$ 2,977
Pro forma net income attributable to L-3	$ 104	$ 168
Pro forma diluted earnings per share	$ 1.24	$ 1.88

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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- Definition

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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