Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 25, 2016	Mar. 27, 2015
Operating activities:
Net cash from (used in) operating activities	$ 112	$ 112
Investing activities:
Business acquisitions, net of cash acquired	(27)	$ (41)
Proceeds from sale of businesses, net of closing date cash balances	$ 576
Investments in L-3 Communications
Other investing activities	$ (19)	$ (33)
Net cash from (used in) investing activities from continuing operations	530	(74)
Financing activities:
Common stock repurchased	(198)	(100)
Dividends paid on L-3 Holdings common stock	$ (58)	$ (58)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	$ (3)	$ 8
Net cash used in financing activities from continuing operations	$ (259)	(150)
Effect of foreign currency exchange rate changes on cash		(11)
Net decrease in cash and cash equivalents of discontinued operations	$ (56)	(3)
Change in cash balance in assets held for sale		1
Net increase (decrease) in cash	$ 327	(125)
Cash and cash equivalents, beginning of the period	207	442
Cash and cash equivalents, end of the period	534	317
L-3 Communications Holdings, Inc. [Member]
Operating activities:
Net cash from (used in) operating activities	$ 256	$ 158
Investing activities:
Business acquisitions, net of cash acquired
Proceeds from sale of businesses, net of closing date cash balances
Investments in L-3 Communications	$ (1)	$ (13)
Other investing activities
Net cash from (used in) investing activities from continuing operations	$ (1)	$ (13)
Financing activities:
Common stock repurchased	(198)	(100)
Dividends paid on L-3 Holdings common stock	$ (58)	$ (58)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	$ 1	$ 13
Net cash used in financing activities from continuing operations	$ (255)	$ (145)
Effect of foreign currency exchange rate changes on cash
Net decrease in cash and cash equivalents of discontinued operations
Change in cash balance in assets held for sale
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 (used in) operating activities	$ 46	$ 107
Investing activities:
Business acquisitions, net of cash acquired	(27)	$ (41)
Proceeds from sale of businesses, net of closing date cash balances	$ 576
Investments in L-3 Communications
Other investing activities	$ 3	$ (19)
Net cash from (used in) investing activities from continuing operations	$ 552	$ (60)
Financing activities:
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings	$ (256)	$ (158)
Investments from L-3 Holdings	1	13
Other financing activities	(131)	(53)
Net cash used in financing activities from continuing operations	$ (386)	$ (198)
Effect of foreign currency exchange rate changes on cash
Net decrease in cash and cash equivalents of discontinued operations
Change in cash balance in assets held for sale
Net increase (decrease) in cash	$ 212	$ (151)
Cash and cash equivalents, beginning of the period	137	361
Cash and cash equivalents, end of the period	349	210
Guarantor Subsidiaries [Member]
Operating activities:
Net cash from (used in) operating activities	$ 117	$ 4
Investing activities:
Business acquisitions, net of cash acquired
Proceeds from sale of businesses, net of closing date cash balances
Investments in L-3 Communications
Other investing activities	$ (12)	$ (5)
Net cash from (used in) investing activities from continuing operations	$ (12)	$ (5)
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	$ (46)	$ 4
Net cash used in financing activities from continuing operations	(46)	$ 4
Effect of foreign currency exchange rate changes on cash
Net decrease in cash and cash equivalents of discontinued operations	(56)	$ (3)
Change in cash balance in assets held for sale		1
Net increase (decrease) in cash	$ 3	1
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	$ (32)	$ 1
Investing activities:
Business acquisitions, net of cash acquired
Proceeds from sale of businesses, net of closing date cash balances
Investments in L-3 Communications
Other investing activities	$ (10)	$ (9)
Net cash from (used in) investing activities from continuing operations	$ (10)	$ (9)
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	$ 66	$ (7)
Net cash used in financing activities from continuing operations	$ 66	(7)
Effect of foreign currency exchange rate changes on cash		$ (11)
Net decrease in cash and cash equivalents of discontinued operations
Change in cash balance in assets held for sale
Net increase (decrease) in cash	$ 24	$ (26)
Cash and cash equivalents, beginning of the period	165	142
Cash and cash equivalents, end of the period	189	116
Eliminations [Member]
Operating activities:
Net cash from (used in) operating activities	$ (275)	$ (158)
Investing activities:
Business acquisitions, net of cash acquired
Proceeds from sale of businesses, net of closing date cash balances
Investments in L-3 Communications	$ 1	$ 13
Other investing activities
Net cash from (used in) investing activities from continuing operations	$ 1	$ 13
Financing activities:
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings	$ 256	$ 158
Investments from L-3 Holdings	(1)	(13)
Other financing activities	107	51
Net cash used in financing activities from continuing operations	$ 362	$ 196
Effect of foreign currency exchange rate changes on cash
Net decrease in cash and cash equivalents of discontinued operations
Change in cash balance in assets held for sale
Net increase (decrease) in cash	$ 88	$ 51
Cash and cash equivalents, beginning of the period	(95)	(62)
Cash and cash equivalents, end of the period	$ (7)	$ (11)