Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 27, 2015	Mar. 28, 2014
Operating activities:
Net cash from (used in) operating activities	$ 87	$ (62)
Investing activities:
Business acquisitions, net of cash acquired	(41)	(57)
Investments in L-3 Communications
Other investing activities	(34)	(29)
Net cash used in investing activities	(75)	(86)
Financing activities:
Common stock repurchased	(100)	(133)
Dividends paid on L-3 Holdings' common stock	(58)	(55)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	31	64
Net cash (used in) from financing activities	(127)	(124)
Effect of foreign currency exchange rate changes on cash	(11)	(1)
Change in cash balance in assets held for sale	1
Net (decrease) increase in cash	(125)	(273)
Cash and cash equivalents, beginning of the period	442	500
Cash and cash equivalents, end of the period	317	227
L-3 Communications Holdings, Inc. [Member]
Operating activities:
Net cash from (used in) operating activities	158	188
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications	(13)	(51)
Other investing activities
Net cash used in investing activities	(13)	(51)
Financing activities:
Common stock repurchased	(100)	(133)
Dividends paid on L-3 Holdings' common stock	(58)	(55)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	13	51
Net cash (used in) from financing activities	(145)	(137)
Effect of foreign currency exchange rate changes on cash
Change in cash balance in assets held for sale
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	36	80
Investing activities:
Business acquisitions, net of cash acquired	(41)	(57)
Investments in L-3 Communications
Other investing activities	(19)	(13)
Net cash used in investing activities	(60)	(70)
Financing activities:
Common stock repurchased
Dividends paid on L-3 Holdings' common stock
Dividends paid to L-3 Holdings	(158)	(188)
Investments from L-3 Holdings	13	51
Other financing activities	18	(74)
Net cash (used in) from financing activities	(127)	(211)
Effect of foreign currency exchange rate changes on cash
Change in cash balance in assets held for sale
Net (decrease) increase in cash	(151)	(201)
Cash and cash equivalents, beginning of the period	361	258
Cash and cash equivalents, end of the period	210	57
Guarantor Subsidiaries [Member]
Operating activities:
Net cash from (used in) operating activities	65	(61)
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications
Other investing activities	(5)	(15)
Net cash used in investing activities	(5)	(15)
Financing activities:
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	(60)	76
Net cash (used in) from financing activities	(60)	76
Effect of foreign currency exchange rate changes on cash
Change in cash balance in assets held for sale	1
Net (decrease) increase in cash	1
Cash and cash equivalents, beginning of the period	1
Cash and cash equivalents, end of the period	2
Non-Guarantor Subsidiaries [Member]
Operating activities:
Net cash from (used in) operating activities	(14)	(34)
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications
Other investing activities	(10)	(1)
Net cash used in investing activities	(10)	(1)
Financing activities:
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	9	(43)
Net cash (used in) from financing activities	9	(43)
Effect of foreign currency exchange rate changes on cash	(11)	(1)
Change in cash balance in assets held for sale
Net (decrease) increase in cash	(26)	(79)
Cash and cash equivalents, beginning of the period	142	261
Cash and cash equivalents, end of the period	116	182
Eliminations [Member]
Operating activities:
Net cash from (used in) operating activities	(158)	(235)
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications	13	51
Other investing activities
Net cash used in investing activities	13	51
Financing activities:
Common stock repurchased
Dividends paid on L-3 Holdings' common stock
Dividends paid to L-3 Holdings	158	188
Investments from L-3 Holdings	(13)	(51)
Other financing activities	51	54
Net cash (used in) from financing activities	196	191
Effect of foreign currency exchange rate changes on cash
Change in cash balance in assets held for sale
Net (decrease) increase in cash	51	7
Cash and cash equivalents, beginning of the period	(62)	(19)
Cash and cash equivalents, end of the period	$ (11)	$ (12)