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		6 Months Ended
	Jun. 28, 2013	Jun. 29, 2012	Jun. 28, 2013	Jun. 29, 2012
Condensed Financial Statements, Captions [Line Items]
Total net sales	$ 3,192	$ 3,143	$ 6,377	$ 6,303
Total cost of sales	2,885	2,812	5,757	5,647
Operating (loss) income	307	331	620	656
Interest expense	(44)	(45)	(87)	(90)
Interest and other income, net	5	3	8	6
(Loss) income from continuing operations before income taxes	268	289	541	572
(Benefit) provision for income taxes	82	98	161	194
Equity in net income of consolidated subsidiaries			0
Income from continuing operations	186	191	380	378
Income from discontinued operations, net of income tax		17		33
Net income	186	208	380	411
Less: Net income attributable to noncontrolling interests	1	3	2	5
Net income attributable to L-3	185	205	378	406
Comprehensive income attributable to L-3	180	168	349	412
L-3 Communications Holdings, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales			0
Total cost of sales	14	16	28	29
Operating (loss) income	(14)	(16)	(28)	(29)
Interest expense	(5)	(5)	(10)	(10)
Interest and other income, net			0
(Loss) income from continuing operations before income taxes	(19)	(21)	(38)	(39)
(Benefit) provision for income taxes	(6)	(7)	(11)	(13)
Equity in net income of consolidated subsidiaries	198	219	405	432
Income from continuing operations		205		406
Net income	185	205	378	406
Less: Net income attributable to noncontrolling interests			0
Net income attributable to L-3	185	205	378	406
Comprehensive income attributable to L-3	180	168	349	412
L-3 Communications Corporation's [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	993	921	1,928	1,825
Total cost of sales	912	837	1,775	1,667
Operating (loss) income	81	84	153	158
Interest expense	(44)	(45)	(87)	(90)
Interest and other income, net	2	2	4	5
(Loss) income from continuing operations before income taxes	39	41	70	73
(Benefit) provision for income taxes	15	13	21	24
Equity in net income of consolidated subsidiaries	161	160	329	324
Income from continuing operations		188		373
Income from discontinued operations, net of income tax		17		33
Net income	185	205	378	406
Less: Net income attributable to noncontrolling interests			0
Net income attributable to L-3	185	205	378	406
Comprehensive income attributable to L-3	180	168	349	412
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	1,721	1,777	3,453	3,547
Total cost of sales	1,555	1,593	3,107	3,194
Operating (loss) income	166	184	346	353
Interest expense			0
Interest and other income, net			0
(Loss) income from continuing operations before income taxes	166	184	346	353
(Benefit) provision for income taxes	48	63	103	120
Equity in net income of consolidated subsidiaries			0
Income from continuing operations		121		233
Net income	118	121	243	233
Less: Net income attributable to noncontrolling interests			0
Net income attributable to L-3	118	121	243	233
Comprehensive income attributable to L-3	117	121	243	236
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	574	535	1,165	1,101
Total cost of sales	514	472	1,044	956
Operating (loss) income	60	63	121	145
Interest expense			0
Interest and other income, net	3	1	4	1
(Loss) income from continuing operations before income taxes	63	64	125	146
(Benefit) provision for income taxes	19	22	37	50
Equity in net income of consolidated subsidiaries			0
Income from continuing operations		42		96
Net income	44	42	88	96
Less: Net income attributable to noncontrolling interests			0
Net income attributable to L-3	44	42	88	96
Comprehensive income attributable to L-3	27	(7)	33	77
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	(96)	(90)	(169)	(170)
Total cost of sales	(110)	(106)	(197)	(199)
Operating (loss) income	14	16	28	29
Interest expense	5	5	10	10
Interest and other income, net			0
(Loss) income from continuing operations before income taxes	19	21	38	39
(Benefit) provision for income taxes	6	7	11	13
Equity in net income of consolidated subsidiaries	(359)	(379)	(734)	(756)
Income from continuing operations		(365)		(730)
Net income	(346)	(365)	(707)	(730)
Less: Net income attributable to noncontrolling interests	1	3	2	5
Net income attributable to L-3	(347)	(368)	(709)	(735)
Comprehensive income attributable to L-3	$ (324)	$ (282)	$ (625)	$ (725)