Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 25, 2016	Mar. 27, 2015
Condensed Financial Statements, Captions [Line Items]
Total net sales	$ 2,353	$ 2,488
Total cost of sales	$ (2,101)	(2,279)
Loss related to business divestitures		(22)
Operating (loss) income	$ 252	187
Interest expense	(41)	(39)
Interest and other income, net	4	3
(Loss) income from continuing operations before income taxes	215	151
Benefit (provision) for income taxes	$ (48)	$ (46)
Equity in net income of consolidated subsidiaries
Income from continuing operations	$ 167	$ 105
Income from discontinued operations, net of income tax	63	4
Net income	230	109
Net income attributable to noncontrolling interests	(3)	(4)
Net income attributable to L-3	227	105
Comprehensive income (loss) attributable to L-3	$ 243	$ 26
L-3 Communications Holdings, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales
Total cost of sales	$ (6)	$ (13)
Loss related to business divestitures
Operating (loss) income	$ (6)	$ (13)
Interest expense
Interest and other income, net
(Loss) income from continuing operations before income taxes	$ (6)	$ (13)
Benefit (provision) for income taxes	1	4
Equity in net income of consolidated subsidiaries	232	114
Income from continuing operations	$ 227	$ 105
Income from discontinued operations, net of income tax
Net income	$ 227	$ 105
Net income attributable to noncontrolling interests
Net income attributable to L-3	$ 227	$ 105
Comprehensive income (loss) attributable to L-3	243	26
L-3 Communications Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	822	796
Total cost of sales	(739)	$ (729)
Loss related to business divestitures
Operating (loss) income	83	$ 67
Interest expense	(41)	(39)
Interest and other income, net	3	3
(Loss) income from continuing operations before income taxes	45	31
Benefit (provision) for income taxes	(10)	(10)
Equity in net income of consolidated subsidiaries	192	84
Income from continuing operations	$ 227	$ 105
Income from discontinued operations, net of income tax
Net income	$ 227	$ 105
Net income attributable to noncontrolling interests
Net income attributable to L-3	$ 227	$ 105
Comprehensive income (loss) attributable to L-3	243	26
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	1,185	1,272
Total cost of sales	(1,068)	(1,172)
Loss related to business divestitures		(3)
Operating (loss) income	$ 117	$ 97
Interest expense
Interest and other income, net
(Loss) income from continuing operations before income taxes	$ 117	$ 97
Benefit (provision) for income taxes	$ (26)	$ (29)
Equity in net income of consolidated subsidiaries
Income from continuing operations	$ 91	$ 68
Income from discontinued operations, net of income tax	63	4
Net income	$ 154	$ 72
Net income attributable to noncontrolling interests
Net income attributable to L-3	$ 154	$ 72
Comprehensive income (loss) attributable to L-3	162	69
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	409	486
Total cost of sales	(357)	(444)
Loss related to business divestitures		(19)
Operating (loss) income	$ 52	$ 23
Interest expense
Interest and other income, net	$ 1
(Loss) income from continuing operations before income taxes	53	$ 23
Benefit (provision) for income taxes	$ (12)	$ (7)
Equity in net income of consolidated subsidiaries
Income from continuing operations	$ 41	$ 16
Income from discontinued operations, net of income tax
Net income	$ 41	$ 16
Net income attributable to noncontrolling interests
Net income attributable to L-3	$ 41	$ 16
Comprehensive income (loss) attributable to L-3	41	(73)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	(63)	(66)
Total cost of sales	69	$ 79
Loss related to business divestitures
Operating (loss) income	$ 6	$ 13
Interest expense
Interest and other income, net
(Loss) income from continuing operations before income taxes	$ 6	$ 13
Benefit (provision) for income taxes	(1)	(4)
Equity in net income of consolidated subsidiaries	(424)	(198)
Income from continuing operations	$ (419)	$ (189)
Income from discontinued operations, net of income tax
Net income	$ (419)	$ (189)
Net income attributable to noncontrolling interests	(3)	(4)
Net income attributable to L-3	(422)	(193)
Comprehensive income (loss) attributable to L-3	$ (446)	$ (22)