Receivables (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Receivables
Trade accounts receivable	$ 1,169	$ 759
Less allowances for doubtful accounts	(11)	(5)
Net trade accounts receivable	1,158	754
Other receivables	333	131
Receivables, net	1,491	885
Net accounts receivable under long-term contracts, due primarily from agencies of the U.S government and their prime contractors	224	196
Recognized sales value of performance not billed and not yet billable to customers	$ 165	145
Average length of long-term contracts	2 years 6 months
Average remaining length of contracts	1 year
Customary fees and cost withholdings that will be paid upon milestone or contract completions	$ 223
Maximum available sale of the accounts receivables under factoring program	970
Amount of sale of receivables	596	$ 479
Maximum limit of programs to sell receivables not accounted for as true sales of receivables	30
Short-term Debt [Member]
Receivables
Amount outstanding of receivables available for sale not accounted for as true sales of receivables	$ 17