Derivative Instruments and Hedging Strategies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Maximum term	546 days	183 days
Foreign Exchange Contract [Member]
Notional amount	$ 2,344	$ 1,352
Foreign currency transaction gains (losses)	3	(7)	(3)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Notional amount	2,000	1,352
Foreign currency transaction gains (losses)	(6)	(7)	(3)
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Notional amount	344
Amount of pre-tax gain recognized in other income (expense) (ineffective portion and amount excluded from effectiveness testing)	9
Gains on derivatives designated as hedges	$ 12