CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 28, 2012	Dec. 31, 2011
Net allowances for billed receivables	$ 27	$ 25
Treasury stock at cost, shares	52,532,762	45,314,918
L-3 Holdings (Parent) [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares outstanding	94,802,315	98,979,411
L-3 Communications [Member]
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