Debt - Additional Information (Detail) (USD $)	0 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended		0 Months Ended
	May 13, 2014	Sep. 26, 2014	May 13, 2014	Sep. 27, 2013 L-3 Communications Holdings, Inc. [Member]	Sep. 26, 2014 L-3 Communications Holdings, Inc. [Member]	Sep. 27, 2013 L-3 Communications Holdings, Inc. [Member]	May 28, 2014 L-3 Communications Corporation [Member] Instruments
Debt Instrument [Line Items]
Senior Notes issued							2
Principal amount of CODES			$ 1,000
Redemption price for CODES			1,000
Redemption date		Jun. 02, 2014
Conversion of converted securities	935,000,000	(160,000,000)
Number of trading days in the conversion period		20 days
Trading day conversion description		(1) for conversion notices received by May 16, 2014 (5 p.m.), the 20 trading day conversion period began on the third trading day following receipt of the conversion notice and (2) for conversion notices received
Excess of conversion value over fair value of the debt component			160,000,000
Interest expense recognized				$ 5,000,000	$ 2,000,000	$ 15,000,000