Receivables (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Receivables [Abstract]
Trade receivables	$ 1,359	$ 1,678
Costs and estimated earnings in excess of billings on uncompleted contracts	632	621
Other receivables	150	122
Allowance for doubtful accounts	(45)	(32)
Total receivables	$ 2,096	$ 2,389