Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Cash Flows (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 26, 2015	Jun. 27, 2014
Operating activities:
Net cash from (used in) operating activities	$ 314	$ 215
Investing activities:
Business acquisitions, net of cash acquired	(260)	$ (57)
Proceeds from sale of businesses, net of closing date cash balances	304
Investments in L-3 Communications
Other investing activities	(79)	$ (60)
Net cash used in investing activities	(35)	(117)
Financing activities:
Proceeds from sale of Senior Notes		996
Retirement of CODES		(935)
Common stock repurchased	(346)	(333)
Dividends paid on L-3 Holdings' common stock	(111)	$ (107)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	36	$ 80
Net cash (used in) from financing activities	(421)	(299)
Effect of foreign currency exchange rate changes on cash	(8)
Change in cash balance in assets held for sale	61
Net (decrease) increase in cash	(89)	(201)
Cash and cash equivalents, beginning of the period	442	500
Cash and cash equivalents, end of the period	353	299
L-3 Communications Holdings, Inc. [Member]
Operating activities:
Net cash from (used in) operating activities	457	$ 1,375
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications	(23)	$ (77)
Net cash used in investing activities	(23)	(77)
Financing activities:
Retirement of CODES		(935)
Common stock repurchased	(346)	(333)
Dividends paid on L-3 Holdings' common stock	(111)	$ (107)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	23	$ 77
Net cash (used in) from financing activities	(434)	$ (1,298)
Net (decrease) increase 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 (used in) operating activities	273	$ 107
Investing activities:
Business acquisitions, net of cash acquired	(260)	$ (57)
Investments in L-3 Communications
Other investing activities	(46)	$ (25)
Net cash used in investing activities	(306)	(82)
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	(457)	$ (1,375)
Investments from L-3 Holdings	23	77
Other financing activities	303	111
Net cash (used in) from financing activities	(131)	(191)
Net (decrease) increase in cash	(164)	(166)
Cash and cash equivalents, beginning of the period	361	258
Cash and cash equivalents, end of the period	197	92
Guarantor Subsidiaries [Member]
Operating activities:
Net cash from (used in) operating activities	144	$ 152
Investing activities:
Business acquisitions, net of cash acquired
Proceeds from sale of businesses, net of closing date cash balances	28
Investments in L-3 Communications
Other investing activities	(25)	$ (24)
Net cash used in investing activities	3	$ (24)
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	(146)	$ (126)
Net cash (used in) from financing activities	(146)	(126)
Change in cash balance in assets held for sale	1
Net (decrease) increase in cash	2	$ 2
Cash and cash equivalents, beginning of the period	1
Cash and cash equivalents, end of the period	3	$ 2
Non-Guarantor Subsidiaries [Member]
Operating activities:
Net cash from (used in) operating activities	(18)	$ 3
Investing activities:
Business acquisitions, net of cash acquired
Proceeds from sale of businesses, net of closing date cash balances	276
Investments in L-3 Communications
Other investing activities	(8)	$ (11)
Net cash used in investing activities	268	$ (11)
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	(280)	$ (40)
Net cash (used in) from financing activities	(280)	(40)
Effect of foreign currency exchange rate changes on cash	(8)
Change in cash balance in assets held for sale	60
Net (decrease) increase in cash	22	(48)
Cash and cash equivalents, beginning of the period	142	261
Cash and cash equivalents, end of the period	164	213
Eliminations [Member]
Operating activities:
Net cash from (used in) operating activities	(542)	$ (1,422)
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications	23	$ 77
Other investing activities
Net cash used in investing activities	23	$ 77
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	457	$ 1,375
Investments from L-3 Holdings	(23)	(77)
Other financing activities	136	58
Net cash (used in) from financing activities	570	1,356
Net (decrease) increase in cash	51	11
Cash and cash equivalents, beginning of the period	(62)	(19)
Cash and cash equivalents, end of the period	$ (11)	$ (8)