Derivatives and Hedging - Notional and fair values of derivative instruments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value
Notional Amount	$ 768	$ 947
Derivative Assets	12	15
Derivative Liabilities	$ 7	14
Term of derivative contract	30 days
Other Current Assets
Derivatives, Fair Value
Derivative Assets	$ 2	6
Amount not offset against collateral, derivative asset	2	4
Other Noncurrent Assets
Derivatives, Fair Value
Derivative Assets	10	9
Amount not offset against collateral, derivative asset	10	9
Other Current Liabilities
Derivatives, Fair Value
Derivative Liabilities	4	7
Amount not offset against collateral, derivative liabilities	4	5
Other Noncurrent Liabilities
Derivatives, Fair Value
Derivative Liabilities	3	7
Amount not offset against collateral, derivative liabilities	2	7
Derivatives accounted for as hedges | Foreign exchange contracts
Derivatives, Fair Value
Notional Amount	531	758
Derivative Assets	12	14
Derivative Liabilities	6	13
Gross Amounts Offset in the Statement of Financial Position	0	(1)
Net Amounts of Assets Presented in the Statement of Financial Position	12	13
Gross Amounts Offset in the Statement of Financial Position	0	(1)
Net Amounts of Liabilities Presented in the Statement of Financial Position	6	12
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value
Notional Amount	237	189
Derivative Assets	0	1
Derivative Liabilities	$ 1	$ 1