Debt (Details) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010
Components of debt and reconciliation to carrying amount
Borrowings under Revolving Credit Facility	$ 10
Less: Current portion of long-term debt	0	[1]	(11)
Carrying amount of long-term debt	4,126	[1]	4,126
L-3 Communications [Member] | 5 7/8% Senior Subordinated Notes [Member]
Components of debt and reconciliation to carrying amount
Senior Subordinated Notes due 2015	0		650
L-3 Communications [Member] | 6 3/8% Senior Subordinated Notes [Member]
Components of debt and reconciliation to carrying amount
Senior Subordinated Notes due 2015	1,000		1,000
Parent Company [Member]
Components of debt and reconciliation to carrying amount
3% Convertible Contingent Debt Securities due 2035	689		700
Principal amount of long-term debt	4,139		4,150
Less: Unamortized discounts	(13)		(13)
Carrying amount of long-term debt	4,126		4,137
Less: Current portion of long-term debt			(11)
Carrying amount of long-term debt	689		687
L-3 Communications [Member]
Components of debt and reconciliation to carrying amount
Borrowings under Revolving Credit Facility	0		0
5.20% Senior Notes due 2019	1,000		1,000
4.75% Senior Notes due 2020	800		800
4.95% Senior Notes due 2021	650		0
Subtotal	3,450		3,450
Less: Current portion of long-term debt			(11)
Carrying amount of long-term debt	$ 4,126		$ 4,126

[1] Unaudited