Finance Receivables - Aging Analysis (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	$ 122,814	$ 113,705
Consumer Segment [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	83,332	78,392
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	846	947
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,282	2,424
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	5,604	7,562
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	12,542	11,497
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	24,513	20,536
Financing Receivable, Year One, Originated, Current Fiscal Year	36,545	35,426
Non-Consumer Segment [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	39,482	35,313
Financing Receivable, Revolving	36,347	32,262
Non-Consumer Segment [Member] | Dealer Loan
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	283	399
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	63	31
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	102	59
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	48	159
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	260	64
Financing Receivable, Year One, Originated, Current Fiscal Year	281	403
Non-Consumer Segment [Member] | Group I [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	34,298	30,132
Financing Receivable, Revolving	33,345	29,095
Non-Consumer Segment [Member] | Group I [Member] | Dealer Loan
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	270	383
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	63	30
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	97	58
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	47	156
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	231	61
Financing Receivable, Year One, Originated, Current Fiscal Year	245	349
Non-Consumer Segment [Member] | Group II [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	2,570	2,900
Financing Receivable, Revolving	2,494	2,834
Non-Consumer Segment [Member] | Group II [Member] | Dealer Loan
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	13	16
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3	1
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1	3
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	28	2
Financing Receivable, Year One, Originated, Current Fiscal Year	31	44
Non-Consumer Segment [Member] | Group III [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	469	301
Financing Receivable, Revolving	462	292
Non-Consumer Segment [Member] | Group III [Member] | Dealer Loan
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1	1
Financing Receivable, Year One, Originated, Current Fiscal Year	4	8
Non-Consumer Segment [Member] | Group IV [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	47	44
Financing Receivable, Revolving	46	41
Non-Consumer Segment [Member] | Group IV [Member] | Dealer Loan
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year One, Originated, Current Fiscal Year	1	2
Financial Asset, 1 to 29 Days Past Due [Member] | Consumer Segment [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	82,185	77,464
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	788	891
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,162	2,360
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	5,465	7,395
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	12,298	11,325
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	24,189	20,281
Financing Receivable, Year One, Originated, Current Fiscal Year	36,283	35,212
31-60 Days Past Due [Member] | Consumer Segment [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	872	690
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	43	40
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	93	49
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	104	130
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	187	125
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	242	187
Financing Receivable, Year One, Originated, Current Fiscal Year	203	159
Financing Receivables, 61-120 Days past due [Member] | Consumer Segment [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	225	195
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	8	9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	20	11
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	27	30
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	46	37
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	70	58
Financing Receivable, Year One, Originated, Current Fiscal Year	54	50
Greater Than 120 Days Past Due [Member] | Consumer Segment [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	50	43
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	7	7
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	7	4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	8	7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	11	10
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	12	10
Financing Receivable, Year One, Originated, Current Fiscal Year	5	5
Total past due [Member] | Consumer Segment [Member]
Finance Receivables Aging Analysis [Abstract]
Financing Receivable, Gross	1,147	928
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	58	56
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	120	64
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	139	167
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	244	172
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	324	255
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 262	$ 214