Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Condensed Financial Statements, Captions [Line Items]
Total net sales	$ 2,505	$ 2,564	$ 7,522	$ 7,595
Total cost of sales	(2,290)	(2,289)	(6,808)	(6,960)
(Loss) gain related to business divestitures		(9)		(29)
Goodwill impairment charges		(35)		(35)
Operating (loss) income	215	231	714	571
Interest expense	(41)	(43)	(125)	(124)
Interest and other income, net	6	3	15	11
Debt retirement charge			(5)
(Loss) income from continuing operations before income taxes	180	191	599	458
Benefit (provision) for income taxes	(29)	(63)	(130)	(105)
Equity in net income of consolidated subsidiaries
Income from continuing operations	151	128	469	353
Income (loss) from discontinued operations, net of income tax		(424)	63	(416)
Net income (loss)	151	(296)	532	(63)
Net income attributable to noncontrolling interests	(3)	(3)	(10)	(11)
Net (loss) income attributable to L-3	148	(299)	522	(74)
Comprehensive (loss) income attributable to L-3	125	(351)	529	(120)
L-3 Communications Holdings, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales
Total cost of sales	(15)	(12)	(34)	(35)
(Loss) gain related to business divestitures
Goodwill impairment charges
Operating (loss) income	(15)	(12)	(34)	(35)
Interest expense
Interest and other income, net
Debt retirement charge
(Loss) income from continuing operations before income taxes	(15)	(12)	(34)	(35)
Benefit (provision) for income taxes	2	4	7	8
Equity in net income of consolidated subsidiaries	161	(291)	549	(47)
Income from continuing operations		(299)	522	(74)
Income (loss) from discontinued operations, net of income tax
Net income (loss)	148	(299)	522	(74)
Net income attributable to noncontrolling interests
Net (loss) income attributable to L-3	148	(299)	522	(74)
Comprehensive (loss) income attributable to L-3	125	(351)	529	(120)
L-3 Communications Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	877	873	2,602	2,548
Total cost of sales	(801)	(793)	(2,343)	(2,332)
(Loss) gain related to business divestitures		(8)		(13)
Goodwill impairment charges
Operating (loss) income	76	72	259	203
Interest expense	(40)	(43)	(124)	(123)
Interest and other income, net	4	2	10	9
Debt retirement charge			(5)
(Loss) income from continuing operations before income taxes	40	31	140	89
Benefit (provision) for income taxes	(7)	(11)	(31)	(20)
Equity in net income of consolidated subsidiaries	115	(319)	413	(143)
Income from continuing operations		(299)	522	(74)
Income (loss) from discontinued operations, net of income tax
Net income (loss)	148	(299)	522	(74)
Net income attributable to noncontrolling interests
Net (loss) income attributable to L-3	148	(299)	522	(74)
Comprehensive (loss) income attributable to L-3	125	(351)	529	(120)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	1,258	1,334	3,817	3,849
Total cost of sales	(1,182)	(1,201)	(3,545)	(3,601)
(Loss) gain related to business divestitures		(1)		(29)
Goodwill impairment charges		(26)		(26)
Operating (loss) income	76	106	272	193
Interest expense				(1)
Interest and other income, net
Debt retirement charge
(Loss) income from continuing operations before income taxes	76	106	272	192
Benefit (provision) for income taxes	(12)	(30)	(59)	(44)
Equity in net income of consolidated subsidiaries
Income from continuing operations		76	213	148
Income (loss) from discontinued operations, net of income tax		(424)	63	(416)
Net income (loss)	64	(348)	276	(268)
Net income attributable to noncontrolling interests
Net (loss) income attributable to L-3	64	(348)	276	(268)
Comprehensive (loss) income attributable to L-3	64	(354)	287	(273)
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	444	443	1,307	1,423
Total cost of sales	(381)	(381)	(1,124)	(1,252)
(Loss) gain related to business divestitures				13
Goodwill impairment charges		(9)		(9)
Operating (loss) income	63	53	183	175
Interest expense	(1)		(1)
Interest and other income, net	2	1	5	2
Debt retirement charge
(Loss) income from continuing operations before income taxes	64	54	187	177
Benefit (provision) for income taxes	(10)	(22)	(40)	(41)
Equity in net income of consolidated subsidiaries
Income from continuing operations		32	147	136
Income (loss) from discontinued operations, net of income tax
Net income (loss)	54	32	147	136
Net income attributable to noncontrolling interests
Net (loss) income attributable to L-3	54	32	147	136
Comprehensive (loss) income attributable to L-3	24	(25)	120	62
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	(74)	(86)	(204)	(225)
Total cost of sales	89	98	238	260
(Loss) gain related to business divestitures
Goodwill impairment charges
Operating (loss) income	15	12	34	35
Interest expense
Interest and other income, net
Debt retirement charge
(Loss) income from continuing operations before income taxes	15	12	34	35
Benefit (provision) for income taxes	(2)	(4)	(7)	(8)
Equity in net income of consolidated subsidiaries	(276)	610	(962)	190
Income from continuing operations		618	(935)	217
Income (loss) from discontinued operations, net of income tax
Net income (loss)	(263)	618	(935)	217
Net income attributable to noncontrolling interests	(3)	(3)	(10)	(11)
Net (loss) income attributable to L-3	(266)	615	(945)	206
Comprehensive (loss) income attributable to L-3	$ (213)	$ 730	$ (936)	$ 331