Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 24, 2016	Jun. 26, 2015	Jun. 24, 2016	Jun. 26, 2015
Condensed Financial Statements, Captions [Line Items]
Total net sales	$ 2,664	$ 2,543	$ 5,017	$ 5,031
Total cost of sales	(2,417)	(2,392)	(4,518)	(4,671)
(Loss) gain related to business divestitures		2		(20)
Operating (loss) income	247	153	499	340
Interest expense	(43)	(42)	(84)	(81)
Interest and other income, net	5	5	9	8
Debt retirement charge	(5)		(5)
(Loss) income from continuing operations before income taxes	204	116	419	267
Benefit (provision) for income taxes	(53)	4	(101)	(42)
Equity in net income of consolidated subsidiaries
Income from continuing operations	151	120	318	225
Income from discontinued operations, net of income tax		4	63	8
Net income	151	124	381	233
Net income attributable to noncontrolling interests	(4)	(4)	(7)	(8)
Net income attributable to L-3	147	120	374	225
Comprehensive income attributable to L-3	161	205	404	231
L-3 Communications Holdings, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales
Total cost of sales	(13)	(10)	(19)	(23)
(Loss) gain related to business divestitures
Operating (loss) income	(13)	(10)	(19)	(23)
Interest expense
Interest and other income, net
Debt retirement charge
(Loss) income from continuing operations before income taxes	(13)	(10)	(19)	(23)
Benefit (provision) for income taxes	4		5	4
Equity in net income of consolidated subsidiaries	156	130	388	244
Income from continuing operations		120	374	225
Income from discontinued operations, net of income tax
Net income	147	120	374	225
Net income attributable to noncontrolling interests
Net income attributable to L-3	147	120	374	225
Comprehensive income attributable to L-3	161	205	404	231
L-3 Communications Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	903	879	1,725	1,675
Total cost of sales	(803)	(810)	(1,542)	(1,539)
(Loss) gain related to business divestitures		(5)		(5)
Operating (loss) income	100	64	183	131
Interest expense	(43)	(41)	(84)	(80)
Interest and other income, net	3	4	6	7
Debt retirement charge	(5)		(5)
(Loss) income from continuing operations before income taxes	55	27	100	58
Benefit (provision) for income taxes	(14)	1	(24)	(9)
Equity in net income of consolidated subsidiaries	106	92	298	176
Income from continuing operations		120	374	225
Income from discontinued operations, net of income tax
Net income	147	120	374	225
Net income attributable to noncontrolling interests
Net income attributable to L-3	147	120	374	225
Comprehensive income attributable to L-3	161	205	404	231
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	1,374	1,243	2,559	2,515
Total cost of sales	(1,295)	(1,228)	(2,363)	(2,400)
(Loss) gain related to business divestitures		(25)		(28)
Operating (loss) income	79	(10)	196	87
Interest expense		(1)		(1)
Interest and other income, net
Debt retirement charge
(Loss) income from continuing operations before income taxes	79	(11)	196	86
Benefit (provision) for income taxes	(21)	15	(47)	(14)
Equity in net income of consolidated subsidiaries
Income from continuing operations		4	149	72
Income from discontinued operations, net of income tax		4	63	8
Net income	58	8	212	80
Net income attributable to noncontrolling interests
Net income attributable to L-3	58	8	212	80
Comprehensive income attributable to L-3	61	12	223	81
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	454	494	863	980
Total cost of sales	(386)	(427)	(743)	(871)
(Loss) gain related to business divestitures		32		13
Operating (loss) income	68	99	120	122
Interest expense
Interest and other income, net	2	1	3	1
Debt retirement charge
(Loss) income from continuing operations before income taxes	70	100	123	123
Benefit (provision) for income taxes	(18)	(12)	(30)	(19)
Equity in net income of consolidated subsidiaries
Income from continuing operations		88	93	104
Income from discontinued operations, net of income tax
Net income	52	88	93	104
Net income attributable to noncontrolling interests
Net income attributable to L-3	52	88	93	104
Comprehensive income attributable to L-3	55	160	96	87
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	(67)	(73)	(130)	(139)
Total cost of sales	80	83	149	162
(Loss) gain related to business divestitures
Operating (loss) income	13	10	19	23
Interest expense
Interest and other income, net
Debt retirement charge
(Loss) income from continuing operations before income taxes	13	10	19	23
Benefit (provision) for income taxes	(4)		(5)	(4)
Equity in net income of consolidated subsidiaries	(262)	(222)	(686)	(420)
Income from continuing operations		(212)	(672)	(401)
Income from discontinued operations, net of income tax
Net income	(253)	(212)	(672)	(401)
Net income attributable to noncontrolling interests	(4)	(4)	(7)	(8)
Net income attributable to L-3	(257)	(216)	(679)	(409)
Comprehensive income attributable to L-3	$ (277)	$ (377)	$ (723)	$ (399)