Condensed Combining Statements of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 28, 2012	Sep. 30, 2011
Operating activities:
Net cash from operating activities from continuing operations	$ 692	$ 749
Investing activities:
Business acquisitions, net of cash acquired	(349)	(15)
Other investing activities	212	(118)
Net cash used in investing activities from continuing operations	(137)	(133)
Financing activities:
Proceeds from sale of senior notes		646
Redemption of senior subordinated notes and CODES	(250)	(661)
Common stock repurchased	(504)	(800)
Dividends paid on L-3 Holdings common stock	(149)	(143)
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	20	43
Net cash used in financing activities from continuing operations	(883)	(915)
Effect of foreign currency exchange rate changes on cash	4
Net increase in cash and cash equivalents of discontinued operations	74	230
Net (decrease) increase in cash	(250)	(69)
Cash and cash equivalents, beginning of the period	764	607
Cash and cash equivalents, end of the period	514	538
L-3 Holdings (Parent) [Member]
Operating activities:
Net cash from operating activities from continuing operations	653	954
Investing activities:
Investments in L-3 Communications	(27)	(42)
Net cash used in investing activities from continuing operations	(27)	(42)
Financing activities:
Redemption of senior subordinated notes and CODES		(11)
Common stock repurchased	(504)	(800)
Dividends paid on L-3 Holdings common stock	(149)	(143)
Other financing activities	27	42
Net cash used in financing activities from continuing operations	(626)	(912)
L-3 Communications [Member]
Operating activities:
Net cash from operating activities from continuing operations	96	131
Investing activities:
Business acquisitions, net of cash acquired	(349)	(15)
Other investing activities	262	(54)
Net cash used in investing activities from continuing operations	(87)	(69)
Financing activities:
Proceeds from sale of senior notes		646
Redemption of senior subordinated notes and CODES	(250)	(650)
Dividends paid to L-3 Holdings	(653)	(954)
Investments from L-3 Holdings	27	42
Other financing activities	510	496
Net cash used in financing activities from continuing operations	(366)	(420)
Net increase in cash and cash equivalents of discontinued operations	74	230
Net (decrease) increase in cash	(283)	(128)
Cash and cash equivalents, beginning of the period	644	251
Cash and cash equivalents, end of the period	361	123
Guarantor Subsidiaries [Member]
Operating activities:
Net cash from operating activities from continuing operations	527	562
Investing activities:
Other investing activities	(41)	(50)
Net cash used in investing activities from continuing operations	(41)	(50)
Financing activities:
Other financing activities	(485)	(512)
Net cash used in financing activities from continuing operations	(485)	(512)
Net (decrease) increase in cash	1
Cash and cash equivalents, end of the period	1
Non-Guarantor Subsidiaries [Member]
Operating activities:
Net cash from operating activities from continuing operations	169	113
Investing activities:
Other investing activities	(9)	(14)
Net cash used in investing activities from continuing operations	(9)	(14)
Financing activities:
Other financing activities	(169)	(98)
Net cash used in financing activities from continuing operations	(169)	(98)
Effect of foreign currency exchange rate changes on cash	4
Net (decrease) increase in cash	(5)	1
Cash and cash equivalents, beginning of the period	222	473
Cash and cash equivalents, end of the period	217	474
Eliminations [Member]
Operating activities:
Net cash from operating activities from continuing operations	(753)	(1,011)
Investing activities:
Investments in L-3 Communications	27	42
Net cash used in investing activities from continuing operations	27	42
Financing activities:
Dividends paid to L-3 Holdings	653	954
Investments from L-3 Holdings	(27)	(42)
Other financing activities	137	115
Net cash used in financing activities from continuing operations	763	1,027
Net (decrease) increase in cash	37	58
Cash and cash equivalents, beginning of the period	(102)	(117)
Cash and cash equivalents, end of the period	$ (65)	$ (59)