Risk Management (Narrative) (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Total outstanding foreign exchange contracts	$ 717,000,000	$ 494,000,000
Credit Concentration Risk
Derivative [Line Items]
Total outstanding foreign exchange contracts	9,000,000
Not Designated As Hedging Instruments
Derivative [Line Items]
Fair value of derivative liabilities	32,000,000	3,000,000
Not Designated As Hedging Instruments | Interest rate swap | Other Liabilities
Derivative [Line Items]
Fair value of derivative liabilities	$ 0	$ 1,000,000