Finance Receivables and Allowance for Credit Losses Allowance for credit losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 880	$ 870	$ 882	$ 845
Finance receivables, net	115,364		112,823
Financing Receivable, Allowance for Credit Loss, Writeoff	(129)	(96)
Financing Receivable, Allowance for Credit Loss, Recovery	42	39
Financing Receivable, Credit Loss, Expense (Reversal)	88	77
Financing Receivable, Allowance for Credit Losses, Other	(3)	5
Financing Receivable, before Allowance for Credit Loss	116,244		113,705
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	$ (2)
Financing Receivable, Threshold Period Past Due, Writeoff	120 days
Commercial Portfolio Segment [Member]
Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 3	7	3	7
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0
Financing Receivable, Allowance for Credit Loss, Recovery	3	1
Financing Receivable, Credit Loss, Expense (Reversal)	(3)	(1)
Financing Receivable, Allowance for Credit Losses, Other	0	0
Financing Receivable, before Allowance for Credit Loss	36,204		35,313
Consumer Portfolio Segment [Member]
Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Loss	877	863	879	$ 838
Financing Receivable, Allowance for Credit Loss, Writeoff	(129)	(96)
Financing Receivable, Allowance for Credit Loss, Recovery	39	38
Financing Receivable, Credit Loss, Expense (Reversal)	91	78
Financing Receivable, Allowance for Credit Losses, Other	(3)	$ 5
Financing Receivable, before Allowance for Credit Loss	80,040		78,392
Retail Installment loans, dealer financing, and other financing [Member]
Allowance for Credit Losses [Line Items]
Finance receivables, net	$ 107,841		$ 105,476