Derivatives and Hedging - Notional and fair values of derivative instruments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Derivatives, Fair Value
Notional Amount	$ 1,003	$ 1,058
Derivative Assets	15	32
Derivative Liabilities	$ 9	18
Term of derivative contract	30 days
Other Current Assets [Member]
Derivatives, Fair Value
Derivative Assets	$ 5	15
Amount not offset against collateral, derivative asset	4	6
Other Noncurrent Assets [Member]
Derivatives, Fair Value
Derivative Assets	10	17
Amount not offset against collateral, derivative asset	10	13
Other Current Liabilities [Member]
Derivatives, Fair Value
Derivative Liabilities	5	13
Amount not offset against collateral, derivative liabilities	4	4
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value
Derivative Liabilities	4	5
Amount not offset against collateral, derivative liabilities	4	1
Derivatives accounted for as hedges [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value
Notional Amount	794	778
Derivative Assets	15	32
Derivative Liabilities	9	18
Gross Amounts Offset in the Statement of Financial Position	(1)	(13)
Net Amounts of Assets Presented in the Statement of Financial Position	14	19
Gross Amounts Offset in the Statement of Financial Position	(1)	(13)
Net Amounts of Liabilities Presented in the Statement of Financial Position	8	5
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value
Notional Amount	209	280
Derivative Assets	0	0
Derivative Liabilities	$ 0	$ 0