Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 27, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Net allowances for billed receivables	$ 14	$ 14
Treasury stock (at cost), shares	73,794,080	73,005,891
L-3 Communications Holdings, Inc. [Member]
Class of Stock [Line Items]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares outstanding	82,562,110	82,040,525
L-3 Communications Corporation [Member]
Class of Stock [Line Items]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100	100
Common stock, shares issued	100	100
Common stock, shares outstanding	100	100