Transfers of Receivables - Derivative Income and Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	$ (594)	$ 194	$ 157
Securitization Transactions [Member]
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	234	75	17
Securitization Transactions [Member] | Related to Variable Interest Entity - Not VIE [Member]
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	(9)	(5)	(11)
Securitization Transactions [Member] | Other, Not Variable Interest Entity Related [Member]
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	113	39	(2)
Securitization Transactions [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Derivative expense/(income) related to securitization transactions [Abstract]
Derivative expense/(income)	$ 130	$ 41	$ 30