Pensions and Other Employee Benefits, Multi-Employer Benefit Plans (Details) $ in Millions		12 Months Ended
		Dec. 31, 2016 USD ($) PensionFunds		Dec. 31, 2015 USD ($)		Dec. 31, 2014 USD ($)
Multiemployer Plans [Line Items]
Contributions by L-3 Communications		$ 26		$ 23		$ 19
Minimum percentage funded to have green zone status rating		80.00%
Percentage of total plan contributions				5.00%		5.00%
Percentage of contributions from reportable segment		63.00%
Expiration date of multiple bargaining agreements		Apr. 28, 2019
Number of pension funds included in Other Pension Funds | PensionFunds		3
IAM National Pension Fund [Member]
Multiemployer Plans [Line Items]
Contributions by L-3 Communications		$ 26	[1]	$ 23	[2]	$ 19	[2]
EIN/Pension Plan Number		51-6031295/002
Pension Protection Act Zone Status	[3]	Green		Green
FIP/RP Status Pending/Implemented	[4]	No
Surcharge Imposed		No
Expiration Date of Collective-Bargaining Agreement, First		Apr. 09, 2017
Expiration Date of Collective-Bargaining Agreement, Last	[5]	Jun. 28, 2019
Other Pension Funds [Member]
Multiemployer Plans [Line Items]
Contributions by L-3 Communications	[6]	$ 0		$ 0		$ 0

[1] At the date the audited financial statements for the Company were issued, the Form 5500 for the plan year ended December 31, 2016 was not available.

[2] Represents [5%] of total plan contributions for the years ended December 31, 2015 and 2014 based on Form 5500.

[3] A zone status rating of green indicates the plan is at least 80% funded.

[4] Funding improvement plan or rehabilitation plan.

[5] The Company is a party to multiple bargaining agreements for multiple projects that require contributions into the IAM National Pension Fund. The most significant of these agreements, expiring April 28, 2019, covers multiple programs in the Company's Aerospace Systems reportable segment and represents 63% of 2016 contributions.

[6] Consists of three pension funds in which the Company's contributions are individually, and in the aggregate, insignificant.