Percentage-of-Completion Contracts (Details) - USD ($) $ in Millions		3 Months Ended							12 Months Ended
	May 26, 2016	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Billed and Unbilled Contract Claims Subject to Uncertainty [Line Items]
Contract Settlement, Amount	$ 150
Proceeds from Contract Settlements			$ 72	$ 62
Contracts Receivable, Claims and Uncertain Amounts											$ 0
Billings in Excess of Cost											45
IRAQ
Billed and Unbilled Contract Claims Subject to Uncertainty [Line Items]
Loss on Contracts					$ 82	$ 44	$ 69	$ 42	$ 153	$ 72
Total Estimated Loss on Contracts					532				532	379	532
Accounts Receivable, Unapproved Contract Claims					116				116	90	25
Deductions (Charges)					28				28	24	$ 16
Unapproved Change Orders, Amount					32				32	80
ChangeOrdersApprovedbyCustomer										26
Costs in Excess of Billings, Current					$ 6				$ 6	$ 128
Scenario, Forecast [Member]
Billed and Unbilled Contract Claims Subject to Uncertainty [Line Items]
Proceeds from Contract Settlements		$ 16