Finance Receivables and Allowance for Credit Losses Allowance for credit losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss	$ 1,285	$ 513	$ 1,285	$ 513	$ 1,231		$ 513	$ 513	$ 589
Finance receivables, net	103,918		103,918				114,317
Financing Receivable, Allowance for Credit Loss, Writeoff	(80)	(117)		(271)
Financing Receivable, Allowance for Credit Loss, Recovery	34	51		96
Provision for Loan, Lease, and Other Losses	93	63		96
Financing Receivable, Allowance for Credit Losses, Other	7	3		3
Financing Receivable, before Allowance for Credit Loss	105,203		105,203				114,830
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss	1,211	496	1,211	496	1,157		496	496	566
Financing Receivable, Allowance for Credit Loss, Writeoff	(80)	(117)	(225)	(254)
Financing Receivable, Allowance for Credit Loss, Recovery	33	45	76	88
Provision for Loan, Lease, and Other Losses	94	70	628	94
Financing Receivable, Allowance for Credit Losses, Other	7	2	(11)	2
Financing Receivable, before Allowance for Credit Loss	74,893		74,893
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss	74	17	74	17	$ 74		17	$ 17	$ 23
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0	(1)	(17)
Financing Receivable, Allowance for Credit Loss, Recovery	1	6	3	8
Provision for Loan, Lease, and Other Losses	(1)	(7)	51	2
Financing Receivable, Allowance for Credit Losses, Other	0	$ 1	(1)	$ 1
Financing Receivable, before Allowance for Credit Loss	30,310		30,310				40,855
Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss						$ 252
Finance receivables, net	252		252
Accounting Standards Update 2016-13 [Member] | Consumer Portfolio Segment [Member]
Finance receivables, net	247		247
Accounting Standards Update 2016-13 [Member] | Commercial Portfolio Segment [Member]
Finance receivables, net	5		5
Retail Installment loans, dealer financing, and other financing [Domain] [Member]
Finance receivables, net	96,418		96,418			105,901	$ 106,131
Retail Installment loans, dealer financing, and other financing [Domain] [Member] | Accounting Standards Update 2016-13 [Member]
Finance receivables, net						$ (230)
Global pandemic [Member]
Financing Receivable, Allowance for Credit Loss	$ 532		$ 532