Derivatives and Hedging (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value
Notional Amount	$ 2,460	$ 2,245
Derivative Assets	210	157
Derivative Liabilities	251	189
Derivatives accounted for as hedges:
Derivatives, Fair Value
Notional Amount	2,155	1,999
Derivative Assets	208	156
Derivative Liabilities	250	188
Interest rate contracts | Derivatives accounted for as hedges:
Derivatives, Fair Value
Notional Amount	336	702
Derivative Assets	17	16
Foreign exchange contracts | Derivatives accounted for as hedges:
Derivatives, Fair Value
Notional Amount	1,819	1,297
Derivative Assets	191	140
Derivative Liabilities	250	188
Foreign exchange contracts | Derivatives not accounted for as hedges:
Derivatives, Fair Value
Notional Amount	305	246
Derivative Assets	2	1
Derivative Liabilities	$ 1	$ 1