Transfers of Receivables - Exposure Based on Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	$ 2,601	$ 1,128
Fair Value of Derivative Liabilities	524	356
Securitization Transactions [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	5	23
Fair Value of Derivative Liabilities	135	54
Related to Variable Interest Entity - Not VIE [Member] | Securitization Transactions [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	5	7
Fair Value of Derivative Liabilities	0	5
Other, Not Variable Interest Entity Related [Member] | Securitization Transactions [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	0	4
Fair Value of Derivative Liabilities	79	30
Variable Interest Entity, Primary Beneficiary [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	0	12
Fair Value of Derivative Liabilities	56	19
Variable Interest Entity, Primary Beneficiary [Member] | Securitization Transactions [Member]
Securitization Transactions [Line Items]
Fair Value of Derivative Assets	0	12
Fair Value of Derivative Liabilities	$ 56	$ 19