Derivatives and Hedging Activities (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Loss on foreign forward contracts and underlying assets and liabilities	$ 3		$ 9
Foreign exchange forward contract not designated as a hedging instrument
Derivatives, Fair Value [Line Items]
Gain (loss) on foreign currency derivative instruments not designated as hedging instruments	(20)	$ (5)	$ 21	$ (5)
Not Designated As Hedging Instrument | Foreign exchange forward contract not designated as a hedging instrument
Derivatives, Fair Value [Line Items]
Maturity of derivatives			1 month
Notional amount of foreign currency derivatives	645		$ 645		$ 697
Cash Flow Hedging | Designated As Hedging Instrument | Foreign exchange forward contract not designated as a hedging instrument
Derivatives, Fair Value [Line Items]
Maturity of derivatives			12 months
Notional amount of foreign currency derivatives	$ 119		$ 119		$ 240