Receivables (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Receivables [Abstract]
Trade receivables	$ 1,267	$ 1,678
Costs and estimated earnings in excess of billings on uncompleted contracts	739	621
Other receivables	136	122
Allowance for doubtful accounts	(54)	(32)
Total receivables	$ 2,088	$ 2,389