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
	Mar. 28, 2014	Mar. 29, 2013
Condensed Financial Statements, Captions [Line Items]
Total net sales	$ 2,957	$ 3,197
Total cost of sales	(2,671)	(2,887)
Operating (loss) income	286	310
Interest expense	(43)	(43)
Interest and other income, net	5	3
(Loss) income before income taxes	248	270
(Provision) benefit for income taxes	(76)	(78)
Equity in net income of consolidated subsidiaries
Net income	172	192
Net income attributable to noncontrolling interests	(2)	(1)
Net income attributable to L-3	170	191
Comprehensive income attributable to L-3	152	167
L-3 Communications Holdings, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales
Total cost of sales	(15)	(14)
Operating (loss) income	(15)	(14)
Interest expense	(5)	(5)
Interest and other income, net
(Loss) income before income taxes	(20)	(19)
(Provision) benefit for income taxes	6	5
Equity in net income of consolidated subsidiaries	184	205
Net income	170	191
Net income attributable to noncontrolling interests
Net income attributable to L-3	170	191
Comprehensive income attributable to L-3	152	167
L-3 Communications Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	863	946
Total cost of sales	(769)	(864)
Operating (loss) income	94	82
Interest expense	(43)	(43)
Interest and other income, net	5	3
(Loss) income before income taxes	56	42
(Provision) benefit for income taxes	(15)	(12)
Equity in net income of consolidated subsidiaries	129	161
Net income	170	191
Net income attributable to noncontrolling interests
Net income attributable to L-3	170	191
Comprehensive income attributable to L-3	152	167
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	1,625	1,740
Total cost of sales	(1,481)	(1,571)
Operating (loss) income	144	169
Interest expense
Interest and other income, net		(1)
(Loss) income before income taxes	144	168
(Provision) benefit for income taxes	(45)	(48)
Equity in net income of consolidated subsidiaries
Net income	99	120
Net income attributable to noncontrolling interests
Net income attributable to L-3	99	120
Comprehensive income attributable to L-3	96	120
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	543	590
Total cost of sales	(495)	(531)
Operating (loss) income	48	59
Interest expense
Interest and other income, net		1
(Loss) income before income taxes	48	60
(Provision) benefit for income taxes	(16)	(18)
Equity in net income of consolidated subsidiaries
Net income	32	42
Net income attributable to noncontrolling interests
Net income attributable to L-3	32	42
Comprehensive income attributable to L-3	15	5
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	(74)	(79)
Total cost of sales	89	93
Operating (loss) income	15	14
Interest expense	5	5
Interest and other income, net
(Loss) income before income taxes	20	19
(Provision) benefit for income taxes	(6)	(5)
Equity in net income of consolidated subsidiaries	(313)	(366)
Net income	(299)	(352)
Net income attributable to noncontrolling interests	(2)	(1)
Net income attributable to L-3	(301)	(353)
Comprehensive income attributable to L-3	$ (263)	$ (292)