Derivatives (Details 6) (Foreign Operations Hedges [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	$ (14)	$ 68	$ (183)
Foreign currency forwards [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(50)	62	(167)
Currency options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	36	0	0
Non-derivative hedging instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	$ 0	$ 6	$ (16)