Finance Receivables and Allowance for Credit Losses Allowance for credit losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 862	$ 876	$ 862	$ 876	$ 880	$ 882	$ 873	$ 845
Finance receivables, net	121,047		121,047			112,823
Financing Receivable, Allowance for Credit Loss, Writeoff	(155)	(105)	(415)	(279)
Financing Receivable, Allowance for Credit Loss, Recovery	41	37	125	114
Financing Receivable, Credit Loss, Expense (Reversal)	99	74	282	191
Financing Receivable, Allowance for Credit Losses, Other	(3)	(3)	(12)	5
Financing Receivable, before Allowance for Credit Loss	$ 121,909		121,909			113,705
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)			$ (20)
Financing Receivable, Threshold Period Past Due, Writeoff	120 days		120 days
Commercial Portfolio Segment [Member]
Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 4	6	$ 4	6	4	3	7	7
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0	(7)	0
Financing Receivable, Allowance for Credit Loss, Recovery	0	0	3	1
Financing Receivable, Credit Loss, Expense (Reversal)	0	(1)	5	(2)
Financing Receivable, Allowance for Credit Losses, Other	0	0	0	0
Financing Receivable, before Allowance for Credit Loss	38,203		38,203			35,313
Consumer Portfolio Segment [Member]
Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Loss	858	870	858	870	$ 876	879	$ 866	$ 838
Financing Receivable, Allowance for Credit Loss, Writeoff	(155)	(105)	(408)	(279)
Financing Receivable, Allowance for Credit Loss, Recovery	41	37	122	113
Financing Receivable, Credit Loss, Expense (Reversal)	99	75	277	193
Financing Receivable, Allowance for Credit Losses, Other	(3)	$ (3)	(12)	$ 5
Financing Receivable, before Allowance for Credit Loss	83,706		83,706			78,392
Retail Installment loans, dealer financing, and other financing [Member]
Allowance for Credit Losses [Line Items]
Finance receivables, net	$ 112,817		$ 112,817			$ 105,476