L-3 Holdings' Earnings Per Common Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 30, 2012	Apr. 01, 2011
Reconciliation of net income:
Net income	$ 203	$ 207
Net income attributable to noncontrolling interests	(2)	(3)
Net income allocable to participating securities		(1)
Net income allocable to L-3 Holdings' common shareholders	$ 201	$ 203
Basic:
Weighted average common shares outstanding	99.0	108.5
Basic earnings per share:
Net income	$ 2.03	$ 1.87
Common and potential common shares:
Weighted average common shares outstanding	99.0	108.5
Assumed purchase of common shares for treasury	(2.4)	(3.5)
Assumed conversion of the CODES
Common and potential common shares	100.2	109.5
Diluted earning per share:
Net income	$ 2.01	$ 1.85
L-3 Holdings' Earnings Per Common Share (Textual)
Conversion price of L-3 Holdings' CODES	$ 96.48
Shares excluded from computation of diluted earnings per share	3.7	2.9
Assumed exercise of stock options [Member]
Common and potential common shares:
Common and potential common shares	1.2	2.8
Unvested restricted stock awards [Member]
Common and potential common shares:
Common and potential common shares	2.0	1.3
Employee stock purchase plan contributions [Member]
Common and potential common shares:
Common and potential common shares	0.3	0.3
Performance unit awards [Member]
Common and potential common shares:
Common and potential common shares	0.1	0.1