Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Operations (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Condensed Financial Statements, Captions [Line Items]
Total net sales	$ 2,996	$ 3,283	$ 9,373	$ 9,586
Total cost of sales	(2,682)	(2,952)	(8,439)	(8,599)
Operating (loss) income	314	331	934	987
Interest expense	(44)	(48)	(131)	(138)
Interest and other income, net	3		11	6
Debt retirement charge		(8)		(8)
(Loss) income from continuing operations before income taxes	273	275	814	847
Benefit (provision) for income taxes	(65)	(80)	(226)	(274)
Equity in net income of consolidated subsidiaries
Income from continuing operations	208	195	588	573
Income (loss) from discontinued operations, net of income tax		(1)		32
Net income	208	194	588	605
Net income attributable to noncontrolling interests	(4)	(2)	(6)	(7)
Net income attributable to L-3	204	192	582	598
Comprehensive income attributable to L-3	254	249	603	661
L-3 Communications Holdings, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales
Total cost of sales	(14)	(15)	(42)	(44)
Operating (loss) income	(14)	(15)	(42)	(44)
Interest expense	(5)	(5)	(15)	(15)
Interest and other income, net
(Loss) income from continuing operations before income taxes	(19)	(20)	(57)	(59)
Benefit (provision) for income taxes	5	6	16	19
Equity in net income of consolidated subsidiaries	218	206	623	638
Income from continuing operations		192		598
Net income	204	192	582	598
Net income attributable to noncontrolling interests
Net income attributable to L-3	204	192	582	598
Comprehensive income attributable to L-3	254	249	603	661
L-3 Communications Corporation's [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	913	892	2,841	2,715
Total cost of sales	(855)	(808)	(2,630)	(2,475)
Operating (loss) income	58	84	211	240
Interest expense	(43)	(48)	(130)	(138)
Interest and other income, net	2	3	6	8
Debt retirement charge		(8)		(8)
(Loss) income from continuing operations before income taxes	17	31	87	102
Benefit (provision) for income taxes	(3)	(9)	(24)	(32)
Equity in net income of consolidated subsidiaries	190	171	519	496
Income from continuing operations		193		566
Income (loss) from discontinued operations, net of income tax		(1)		32
Net income	204	192	582	598
Net income attributable to noncontrolling interests
Net income attributable to L-3	204	192	582	598
Comprehensive income attributable to L-3	254	249	603	661
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	1,636	1,929	5,089	5,476
Total cost of sales	(1,443)	(1,743)	(4,550)	(4,936)
Operating (loss) income	193	186	539	540
Interest expense
Interest and other income, net	1	(4)	1	(4)
(Loss) income from continuing operations before income taxes	194	182	540	536
Benefit (provision) for income taxes	(47)	(53)	(150)	(173)
Equity in net income of consolidated subsidiaries
Income from continuing operations		129		363
Net income	147	129	390	363
Net income attributable to noncontrolling interests
Net income attributable to L-3	147	129	390	363
Comprehensive income attributable to L-3	148	129	391	366
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	546	550	1,711	1,648
Total cost of sales	(483)	(489)	(1,527)	(1,441)
Operating (loss) income	63	61	184	207
Interest expense	(1)		(1)
Interest and other income, net		1	4	2
(Loss) income from continuing operations before income taxes	62	62	187	209
Benefit (provision) for income taxes	(15)	(18)	(52)	(69)
Equity in net income of consolidated subsidiaries
Income from continuing operations		44		140
Net income	47	44	135	140
Net income attributable to noncontrolling interests
Net income attributable to L-3	47	44	135	140
Comprehensive income attributable to L-3	79	92	112	168
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	(99)	(88)	(268)	(253)
Total cost of sales	113	103	310	297
Operating (loss) income	14	15	42	44
Interest expense	5	5	15	15
Interest and other income, net
(Loss) income from continuing operations before income taxes	19	20	57	59
Benefit (provision) for income taxes	(5)	(6)	(16)	(19)
Equity in net income of consolidated subsidiaries	(408)	(377)	(1,142)	(1,134)
Income from continuing operations		(363)		(1,094)
Net income	(394)	(363)	(1,101)	(1,094)
Net income attributable to noncontrolling interests	(4)	(2)	(6)	(7)
Net income attributable to L-3	(398)	(365)	(1,107)	(1,101)
Comprehensive income attributable to L-3	$ (481)	$ (470)	$ (1,106)	$ (1,195)