Derivative Financial Instruments and Cash Flow Hedging Strategy General Cash Flow Hedge Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Notional Amount of Foreign Currency Cash Flow Hedge Derivatives	$ 235	$ 254
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	13
Maximum Length of Time Hedged in Cash Flow Hedge	0 years 24 months 0 days
Minimum [Member]
Derivative [Line Items]
Revenue, Net, Percent denominated in Non-US Currencies	60.00%
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount of Foreign Currency Derivatives	$ 142	$ 116