Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Balance Sheets (Detail) - USD ($) $ in Millions	Sep. 23, 2016	Dec. 31, 2015	Sep. 25, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 411	$ 207	$ 323	$ 442
Billed receivables, net	812	746
Contracts in process	2,265	2,081
Other current assets	521	534
Assets of discontinued operations		664
Total current assets	4,009	4,232
Goodwill	6,284	6,281
Other assets	1,518	1,554
Investment in and amounts due from consolidated subsidiaries
Total assets	11,811	12,067
Current portion of long-term debt	549	499
Current liabilities	2,201	2,160
Liabilities of discontinued operations		220
Amounts due to consolidated subsidiaries
Other long-term liabilities	1,639	1,634
Long-term debt	2,782	3,125
Total liabilities	7,171	7,638
L-3 shareholders' equity	4,568	4,355
Noncontrolling interests	72	74
Total equity	4,640	4,429	4,659	5,360
Total liabilities and equity	11,811	12,067
L-3 Communications Holdings, Inc. [Member]
Current assets:
Cash and cash equivalents
Billed receivables, net
Contracts in process
Other current assets
Assets of discontinued operations
Total current assets
Goodwill
Other assets
Investment in and amounts due from consolidated subsidiaries	4,568	4,355
Total assets	4,568	4,355
Current portion of long-term debt
Current liabilities
Liabilities of discontinued operations
Amounts due to consolidated subsidiaries
Other long-term liabilities
Long-term debt
Total liabilities
L-3 shareholders' equity	4,568	4,355
Noncontrolling interests
Total equity	4,568	4,355
Total liabilities and equity	4,568	4,355
L-3 Communications Corporation [Member]
Current assets:
Cash and cash equivalents	188	137	170	361
Billed receivables, net	319	278
Contracts in process	959	872
Other current assets	273	288
Assets of discontinued operations
Total current assets	1,739	1,575
Goodwill	2,338	2,318
Other assets	765	798
Investment in and amounts due from consolidated subsidiaries	5,368	5,609
Total assets	10,210	10,300
Current portion of long-term debt	549	499
Current liabilities	892	911
Liabilities of discontinued operations
Amounts due to consolidated subsidiaries
Other long-term liabilities	1,419	1,410
Long-term debt	2,782	3,125
Total liabilities	5,642	5,945
L-3 shareholders' equity	4,568	4,355
Noncontrolling interests
Total equity	4,568	4,355
Total liabilities and equity	10,210	10,300
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents			1	1
Billed receivables, net	277	297
Contracts in process	1,053	958
Other current assets	139	137
Assets of discontinued operations		664
Total current assets	1,469	2,056
Goodwill	2,973	2,973
Other assets	490	496
Investment in and amounts due from consolidated subsidiaries	4,433	3,739
Total assets	9,365	9,264
Current portion of long-term debt
Current liabilities	856	899
Liabilities of discontinued operations		220
Amounts due to consolidated subsidiaries
Other long-term liabilities	191	195
Long-term debt
Total liabilities	1,047	1,314
L-3 shareholders' equity	8,318	7,950
Noncontrolling interests
Total equity	8,318	7,950
Total liabilities and equity	9,365	9,264
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	239	165	167	142
Billed receivables, net	216	171
Contracts in process	253	251
Other current assets	109	109
Assets of discontinued operations
Total current assets	817	696
Goodwill	973	990
Other assets	263	260
Investment in and amounts due from consolidated subsidiaries		111
Total assets	2,053	2,057
Current portion of long-term debt
Current liabilities	469	445
Liabilities of discontinued operations
Amounts due to consolidated subsidiaries	159
Other long-term liabilities	29	29
Long-term debt
Total liabilities	657	474
L-3 shareholders' equity	1,396	1,583
Noncontrolling interests
Total equity	1,396	1,583
Total liabilities and equity	2,053	2,057
Eliminations [Member]
Current assets:
Cash and cash equivalents	(16)	(95)	$ (15)	$ (62)
Billed receivables, net
Contracts in process
Other current assets
Assets of discontinued operations
Total current assets	(16)	(95)
Goodwill
Other assets
Investment in and amounts due from consolidated subsidiaries	(14,369)	(13,814)
Total assets	(14,385)	(13,909)
Current portion of long-term debt
Current liabilities	(16)	(95)
Liabilities of discontinued operations
Amounts due to consolidated subsidiaries	(159)
Other long-term liabilities
Long-term debt
Total liabilities	(175)	(95)
L-3 shareholders' equity	(14,282)	(13,888)
Noncontrolling interests	72	74
Total equity	(14,210)	(13,814)
Total liabilities and equity	$ (14,385)	$ (13,909)