Transfers of Receivables - Exposure Based on Fair Value of Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	$ 865	$ 1,256
Fair Value of Derivative Liabilities	555	400
Variable Interest Entity, Primary Beneficiary [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	4	4
Fair Value of Derivative Liabilities	76	134
Securitization Transactions [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	38	89
Fair Value of Derivative Liabilities	115	219
Variable Interest Entity, Primary Beneficiary [Member] | Securitization Transactions [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	4	4
Fair Value of Derivative Liabilities	76	134
Related to Variable Interest Entity - Not VIE [Member] | Securitization Transactions [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	30	74
Fair Value of Derivative Liabilities	28	63
Other, Not Variable Interest Entity Related [Member] | Securitization Transactions [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	4	11
Fair Value of Derivative Liabilities	$ 11	$ 22