Derivative Instruments (Narrative) (Details) - Cash Flow Hedging - Designated as Hedging Instrument - Foreign exchange forward contracts - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Derivative [Line Items]
Net gains related to derivatives recorded in other comprehensive income (loss) expected to be reclassified into earnings	$ 7
Aggregate notional value	$ 255	$ 112

The estimated value of gains (losses), net anticipated to be transferred in the future from accumulated other comprehensive income into earnings.

No definition available.

Name:	us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration