Debt (Details Textual) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended							1 Months Ended												3 Months Ended
	Mar. 30, 2012	Feb. 03, 2012	Dec. 31, 2011	Mar. 30, 2012 3% Convertible Contingent Debt Securities due 2035 [Member]	Mar. 30, 2012 L-3 Communications [Member]	Feb. 03, 2012 L-3 Communications [Member]	Dec. 31, 2011 L-3 Communications [Member]	Feb. 03, 2012 L-3 Communications [Member] Minimum [Member]	Feb. 03, 2012 L-3 Communications [Member] Maximum [Member]	Mar. 30, 2012 L-3 Communications [Member] 3.95% Senior Notes due 2016 [Member]	Dec. 31, 2011 L-3 Communications [Member] 3.95% Senior Notes due 2016 [Member]	Mar. 30, 2012 L-3 Communications [Member] 5.20% Senior Notes due 2019 [Member]	Dec. 31, 2011 L-3 Communications [Member] 5.20% Senior Notes due 2019 [Member]	Mar. 30, 2012 L-3 Communications [Member] 4.75% Senior Notes due 2020 [Member]	Dec. 31, 2011 L-3 Communications [Member] 4.75% Senior Notes due 2020 [Member]	Mar. 30, 2012 L-3 Communications [Member] 4.95% Senior Notes due 2021 [Member]	Dec. 31, 2011 L-3 Communications [Member] 4.95% Senior Notes due 2021 [Member]	Mar. 30, 2012 L-3 Communications [Member] 6 3/8% Senior Subordinated Notes due 2015 [Member]	Dec. 31, 2011 L-3 Communications [Member] 6 3/8% Senior Subordinated Notes due 2015 [Member]	Mar. 30, 2012 L-3 Holdings (Parent) [Member]	Apr. 01, 2011 L-3 Holdings (Parent) [Member]	May 07, 2012 L-3 Holdings (Parent) [Member]	Mar. 30, 2012 L-3 Holdings (Parent) [Member] 3% Convertible Contingent Debt Securities due 2035 [Member]	Dec. 31, 2011 L-3 Holdings (Parent) [Member] 3% Convertible Contingent Debt Securities due 2035 [Member]	Jan. 31, 2011 L-3 Holdings (Parent) [Member] 3% Convertible Contingent Debt Securities due 2035 [Member]
Debt (Textual)
Interest rate on senior notes				3.00%						3.95%	3.95%	5.20%	5.20%	4.75%	4.75%	4.95%	4.95%	6.375%	6.375%				3.00%	3.00%
Current convertible common stock price																							$ 115.78
Common stock, shares																				7.0
Closing stock price																						$ 71.41
Effective interest rate																									6.33%
Interest expense recognized																				$ 5,000,000	$ 7,000,000
Base rate above the latest federal funds rate						0.50%
Base rate above a Eurodollar rate						1.00%
Applicable spread on base rate option								0.25%	1.00%
Applicable spread on Eurodollar rate option								1.25%	2.00%
Commitment fees calculated on the daily amounts of the available unused commitments								0.15%	0.325%
Letter of credit fees for performance and commercial letters of credit								0.675%	1.20%
Letter of credit fees for financial letters of credit								1.25%	2.00%
Length of credit facility	3 years
Total aggregate borrowings under revolving credit facility		1,000,000,000
Available borrowings under revolving credit facility	996,000,000
Outstanding letters of credit	4,000,000
Excess of current common stock price over common stock conversion price	120.00%
Conversion price of L-3 Holdings' CODES	$ 96.48
Carrying amount of the equity component (conversion feature)	64,000,000		64,000,000
Uncommitted incremental revolving facilities and additional term loan facilities		$ 500,000,000