Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 26, 2014	Sep. 27, 2013
Operating activities:
Net cash from operating activities	$ 605	$ 617
Investing activities:
Business acquisitions, net of cash acquired	(57)	(2)
Investments in L-3 Communications
Other investing activities	(105)	(139)
Net cash used in investing activities	(162)	(141)
Financing activities:
Proceeds from sale of senior notes	996
Retirement of CODES	(935)
Common stock repurchased	(413)	(404)
Dividends paid on L-3 Holdings common stock	(158)	(151)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	84	109
Net cash used in financing activities	(426)	(446)
Effect of foreign currency exchange rate changes on cash	(9)	(2)
Net increase (decrease) in cash	8	28
Cash and cash equivalents, beginning of the period	500	349
Cash and cash equivalents, end of the period	508	377
L-3 Communications Holdings, Inc. [Member]
Operating activities:
Net cash from operating activities	1,506	555
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications	(87)	(104)
Other investing activities
Net cash used in investing activities	(87)	(104)
Financing activities:
Proceeds from sale of senior notes
Retirement of CODES	(935)
Common stock repurchased	(413)	(404)
Dividends paid on L-3 Holdings common stock	(158)	(151)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	87	104
Net cash used in financing activities	(1,419)	(451)
Effect of foreign currency exchange rate changes on cash
Net increase (decrease) in cash
Cash and cash equivalents, beginning of the period
Cash and cash equivalents, end of the period
L-3 Communications Corporation [Member]
Operating activities:
Net cash from operating activities	201	86
Investing activities:
Business acquisitions, net of cash acquired	(57)	(2)
Investments in L-3 Communications
Other investing activities	(37)	(70)
Net cash used in investing activities	(94)	(72)
Financing activities:
Proceeds from sale of senior notes	996
Retirement of CODES
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings	(1,506)	(555)
Investments from L-3 Holdings	87	104
Other financing activities	388	345
Net cash used in financing activities	(35)	(106)
Effect of foreign currency exchange rate changes on cash
Net increase (decrease) in cash	72	(92)
Cash and cash equivalents, beginning of the period	258	246
Cash and cash equivalents, end of the period	330	154
Guarantor Subsidiaries [Member]
Operating activities:
Net cash from operating activities	382	523
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications
Other investing activities	(52)	(53)
Net cash used in investing activities	(52)	(53)
Financing activities:
Proceeds from sale of senior notes
Retirement of CODES
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	(329)	(469)
Net cash used in financing activities	(329)	(469)
Effect of foreign currency exchange rate changes on cash
Net increase (decrease) in cash	1	1
Cash and cash equivalents, beginning of the period
Cash and cash equivalents, end of the period	1	1
Non-Guarantor Subsidiaries [Member]
Operating activities:
Net cash from operating activities	69	101
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications
Other investing activities	(16)	(16)
Net cash used in investing activities	(16)	(16)
Financing activities:
Proceeds from sale of senior notes
Retirement of CODES
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	(66)	(81)
Net cash used in financing activities	(66)	(81)
Effect of foreign currency exchange rate changes on cash	(9)	(2)
Net increase (decrease) in cash	(22)	2
Cash and cash equivalents, beginning of the period	261	242
Cash and cash equivalents, end of the period	239	244
Eliminations [Member]
Operating activities:
Net cash from operating activities	(1,553)	(648)
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications	87	104
Other investing activities
Net cash used in investing activities	87	104
Financing activities:
Proceeds from sale of senior notes
Retirement of CODES
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings	1,506	555
Investments from L-3 Holdings	(87)	(104)
Other financing activities	4	210
Net cash used in financing activities	1,423	661
Effect of foreign currency exchange rate changes on cash
Net increase (decrease) in cash	(43)	117
Cash and cash equivalents, beginning of the period	(19)	(139)
Cash and cash equivalents, end of the period	$ (62)	$ (22)