Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 25, 2015	Jun. 26, 2015	Mar. 27, 2015	Dec. 31, 2014	Sep. 26, 2014	Jun. 27, 2014	Mar. 28, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Total net sales	$ 2,871	$ 2,564	$ 2,543	$ 2,488	$ 2,961	$ 2,653	$ 2,702	$ 2,670	$ 10,466	$ 10,986	$ 11,420
Total cost of sales									(9,576)	$ (9,974)	$ (10,303)
(Loss) gain related to business divestitures									(31)
Impairment charge	(455)								(384)	$ 0	$ 0
Operating (loss) income	(96)	231	153	187	294	235	217	266	475	1,012	1,117
Interest expense									(169)	(158)	(157)
Interest and other income (expense), net									17	18	20
Debt retirement charge									(1)
(Loss) income from continuing operations before income taxes									322	872	980
Benefit (provision) for income taxes									(25)	(227)	(264)
Income from continuing operations	(56)	128	120	105	205	146	131	163	297	645	716
Income from discontinued operations, net of income tax									(522)	32	44
Net (loss) income	(162)	(296)	124	109	207	157	141	172	(225)	677	760
Net income attributable to noncontrolling interests									(15)	(13)	(9)
Net (loss) income attributable to L-3	$ (166)	$ (299)	$ 120	$ 105	$ 203	$ 154	$ 137	$ 170	(240)	664	751
Comprehensive (loss) income attributable to L-3									(230)	190	1,191
L-3 Communications Holdings, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Total cost of sales									(46)	(50)	(56)
Operating (loss) income									(46)	(50)	(56)
Interest expense										(2)	(21)
(Loss) income from continuing operations before income taxes									(46)	(52)	(77)
Benefit (provision) for income taxes									4	14	21
Equity in net income of consolidated subsidiaries									(198)	702	807
Income from continuing operations									(240)	664	751
Net (loss) income									(240)	664	751
Net (loss) income attributable to L-3									(240)	664	751
Comprehensive (loss) income attributable to L-3									(230)	190	1,191
L-3 Communications Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales									3,580	3,586	3,874
Total cost of sales									(3,283)	(3,255)	(3,595)
(Loss) gain related to business divestitures									(13)
Operating (loss) income									284	331	279
Interest expense									(167)	(156)	(156)
Interest and other income (expense), net									16	15	15
Debt retirement charge									(1)
(Loss) income from continuing operations before income taxes									132	190	138
Benefit (provision) for income taxes									(10)	(49)	(38)
Equity in net income of consolidated subsidiaries									(362)	523	651
Income from continuing operations									(240)	664	751
Net (loss) income									(240)	664	751
Net (loss) income attributable to L-3									(240)	664	751
Comprehensive (loss) income attributable to L-3									(230)	190	1,191
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales									5,265	5,460	5,555
Total cost of sales									(4,906)	(5,017)	(4,971)
(Loss) gain related to business divestitures									(31)
Impairment charge									(364)
Operating (loss) income									(36)	443	584
Interest expense									(1)	(2)
(Loss) income from continuing operations before income taxes									(37)	441	584
Benefit (provision) for income taxes									3	(115)	(157)
Income from continuing operations									(34)	326	427
Income from discontinued operations, net of income tax									(522)	32	44
Net (loss) income									(556)	358	471
Net (loss) income attributable to L-3									(556)	358	471
Comprehensive (loss) income attributable to L-3									(560)	356	469
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales									1,935	2,218	2,362
Total cost of sales									(1,701)	(1,980)	(2,108)
(Loss) gain related to business divestitures									13
Impairment charge									(20)
Operating (loss) income									227	238	254
Interest expense									(1)		(1)
Interest and other income (expense), net									1	3	5
(Loss) income from continuing operations before income taxes									227	241	258
Benefit (provision) for income taxes									(18)	(63)	(69)
Income from continuing operations									209	178	189
Net (loss) income									209	178	189
Net (loss) income attributable to L-3									209	178	189
Comprehensive (loss) income attributable to L-3									98	47	164
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales									(314)	(278)	(371)
Total cost of sales									360	328	427
Operating (loss) income									46	50	56
Interest expense										2	21
(Loss) income from continuing operations before income taxes									46	52	77
Benefit (provision) for income taxes									(4)	(14)	(21)
Equity in net income of consolidated subsidiaries									560	(1,225)	(1,458)
Income from continuing operations									602	(1,187)	(1,402)
Net (loss) income									602	(1,187)	(1,402)
Net income attributable to noncontrolling interests									(15)	(13)	(9)
Net (loss) income attributable to L-3									587	(1,200)	(1,411)
Comprehensive (loss) income attributable to L-3									$ 692	$ (593)	$ (1,824)