Transfers of Receivables - Derivative Income and Expense (Details) (Securitization Transactions [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	$ 239	$ 61	$ 167
Variable Interest Entity, Primary Beneficiary [Member]
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	227	31	225
Related to Variable Interest Entity - Not VIE [Member]
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	(5)	11	(73)
Other, Not Variable Interest Entity Related [Member]
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	$ 17	$ 19	$ 15