Finance Receivables and Loans, Net - Schedule of Loan Modifications (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) loan	Jun. 30, 2024 USD ($) loan	Dec. 31, 2024 USD ($)
Financing Receivable, Troubled Debt Restructuring
Trial modifications, term			3 months
Trial modifications, amount	$ 4		$ 4		$ 4		$ 4
Total	249	$ 116	$ 382	$ 323
Percentage of total			0.30%	0.20%
Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	3	11	$ 6	$ 11
Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	160	98	286	299
Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	2	2	2	4
Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	83	5	83	9
Combination
Financing Receivable, Troubled Debt Restructuring
Total	1	0	5	0
Consumer
Financing Receivable, Troubled Debt Restructuring
Total	134	105	235	204	459	$ 382
Consumer | Current
Financing Receivable, Troubled Debt Restructuring
Total					365	293
Consumer | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total					60	57
Consumer | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total					22	20
Consumer | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total					12	12
Consumer | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	0	0	0	0
Consumer | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	131	98	229	191
Consumer | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	2	2	2	4
Consumer | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	0	5	0	9
Consumer | Combination
Financing Receivable, Troubled Debt Restructuring
Total	1	0	4	0
Consumer | Automotive
Financing Receivable, Troubled Debt Restructuring
Total	132	99	231	193	$ 454	$ 365
Number of loans redefaulted | loan					2,053	787
Amortized cost of loans redefaulted					$ 50	$ 18
Consumer | Automotive | Current
Financing Receivable, Troubled Debt Restructuring
Total					362	281
Consumer | Automotive | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total					59	56
Consumer | Automotive | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total					21	19
Consumer | Automotive | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total					12	9
Consumer | Automotive | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0	$ 0	$ 0
Payment extensions, number of months extended/deferred	30 months	29 months	30 months	29 months
Consumer | Automotive | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	$ 130	$ 97	$ 228	$ 190	447	359
Consumer | Automotive | Contractual maturity extensions | Current
Financing Receivable, Troubled Debt Restructuring
Total					360	280
Consumer | Automotive | Contractual maturity extensions | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total					59	56
Consumer | Automotive | Contractual maturity extensions | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total					21	19
Consumer | Automotive | Contractual maturity extensions | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total					7	4
Consumer | Automotive | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	2	2	2	3	5	5
Principal forgiveness, amount forgiven	0	1	1	1
Consumer | Automotive | Principal forgiveness | Current
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Automotive | Principal forgiveness | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Automotive | Principal forgiveness | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Automotive | Principal forgiveness | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total					5	5
Consumer | Automotive | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0	$ 0	$ 0
Interest rate concessions, initial rate	0.00%	0.00%	0.00%	0.00%
Interest rate concessions, revised rate	0.00%	0.00%	0.00%	0.00%
Consumer | Automotive | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0	$ 1	$ 0	2	1
Interest rate concessions, initial rate	0.00%	0.00%	13.40%	0.00%
Interest rate concessions, revised rate	0.00%	0.00%	7.80%	0.00%
Payment extensions, initial term			67 months
Payment extensions, revised term			90 months
Consumer | Automotive | Combination | Current
Financing Receivable, Troubled Debt Restructuring
Total					2	1
Consumer | Automotive | Combination | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Automotive | Combination | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Automotive | Combination | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Consumer mortgage finance receivables
Financing Receivable, Troubled Debt Restructuring
Total	$ 2	$ 1	$ 4	$ 1	5	3
Consumer | Consumer mortgage finance receivables | Current
Financing Receivable, Troubled Debt Restructuring
Total					3	3
Consumer | Consumer mortgage finance receivables | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total					1	0
Consumer | Consumer mortgage finance receivables | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total					1	0
Consumer | Consumer mortgage finance receivables | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Consumer mortgage finance receivables | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0	$ 0	$ 0
Payment extensions, number of months extended/deferred	167 months	224 months	175 months	223 months
Consumer | Consumer mortgage finance receivables | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	$ 1	$ 1	$ 1	$ 1	2	2
Consumer | Consumer mortgage finance receivables | Contractual maturity extensions | Current
Financing Receivable, Troubled Debt Restructuring
Total					0	2
Consumer | Consumer mortgage finance receivables | Contractual maturity extensions | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total					1	0
Consumer | Consumer mortgage finance receivables | Contractual maturity extensions | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total					1	0
Consumer | Consumer mortgage finance receivables | Contractual maturity extensions | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Consumer mortgage finance receivables | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0	0	0	0
Principal forgiveness, amount forgiven	0	0	0	0
Consumer | Consumer mortgage finance receivables | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0	$ 0	$ 0
Interest rate concessions, initial rate	0.00%	0.00%	0.00%	0.00%
Interest rate concessions, revised rate	0.00%	0.00%	0.00%	0.00%
Consumer | Consumer mortgage finance receivables | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 1	$ 0	$ 3	$ 0	3	1
Payment extensions, number of months extended/deferred	155 months		155 months
Interest rate concessions, initial rate	2.90%	0.00%	3.60%	0.00%
Interest rate concessions, revised rate	2.00%	0.00%	2.30%	0.00%
Payment extensions, initial term	317 months		305 months
Payment extensions, revised term	420 months		447 months
Consumer | Consumer mortgage finance receivables | Combination | Current
Financing Receivable, Troubled Debt Restructuring
Total					3	1
Consumer | Consumer mortgage finance receivables | Combination | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Consumer mortgage finance receivables | Combination | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Consumer mortgage finance receivables | Combination | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Consumer | Other
Financing Receivable, Troubled Debt Restructuring
Total		$ 5		$ 10		14
Consumer | Other | Current
Financing Receivable, Troubled Debt Restructuring
Total						9
Consumer | Other | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total						1
Consumer | Other | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total						1
Consumer | Other | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total						3
Consumer | Other | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total		0		0
Consumer | Other | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total		0		0
Consumer | Other | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total		0		1
Principal forgiveness, amount forgiven		0		1
Consumer | Other | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total		$ 5		$ 9		14
Interest rate concessions, initial rate		30.40%		30.40%
Interest rate concessions, revised rate		9.80%		8.00%
Consumer | Other | Interest rate concessions | Current
Financing Receivable, Troubled Debt Restructuring
Total						9
Consumer | Other | Interest rate concessions | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total						1
Consumer | Other | Interest rate concessions | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total						1
Consumer | Other | Interest rate concessions | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total						3
Consumer | Other | Combination
Financing Receivable, Troubled Debt Restructuring
Total		$ 0		$ 0
Interest rate concessions, initial rate		0.00%		0.00%
Interest rate concessions, revised rate		0.00%		0.00%
Commercial
Financing Receivable, Troubled Debt Restructuring
Total	$ 115	$ 11	$ 147	$ 119	187	119
Commercial | Pass
Financing Receivable, Troubled Debt Restructuring
Total					39	53
Commercial | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					29	0
Commercial | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					118	66
Commercial | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					1	0
Commercial | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 3	$ 11	$ 6	$ 11
Payment extensions, number of months extended/deferred	12 months	7 months	14 months	39 months
Commercial | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	$ 29	$ 0	$ 57	$ 108
Commercial | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0	0	0	0
Principal forgiveness, amount forgiven	0	0	0	0
Commercial | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 83	$ 0	$ 83	$ 0
Interest rate concessions, initial rate	11.80%	0.00%	11.80%	0.00%
Interest rate concessions, revised rate	7.20%	0.00%	7.20%	0.00%
Commercial | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0	$ 1	$ 0
Interest rate concessions, initial rate	0.00%	0.00%	5.00%	0.00%
Interest rate concessions, revised rate	0.00%	0.00%	3.00%	0.00%
Payment extensions, initial term			29 months
Payment extensions, revised term			34 months
Commercial | Automotive
Financing Receivable, Troubled Debt Restructuring
Total	$ 67	$ 11	$ 67	$ 11	67	11
Commercial | Automotive | Pass
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Commercial | Automotive | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Commercial | Automotive | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					67	11
Commercial | Automotive | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Commercial | Automotive | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 3	$ 11	$ 3	$ 11	3	11
Payment extensions, number of months extended/deferred	10 months	7 months	10 months	7 months
Commercial | Automotive | Payment deferrals | Pass
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Commercial | Automotive | Payment deferrals | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Commercial | Automotive | Payment deferrals | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					3	11
Commercial | Automotive | Payment deferrals | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Commercial | Automotive | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0	$ 0	$ 0
Commercial | Automotive | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0	0	0	0
Principal forgiveness, amount forgiven	0	0	0	0
Commercial | Automotive | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 64	$ 0	$ 64	$ 0	64
Interest rate concessions, initial rate	12.10%	0.00%	12.10%	0.00%
Interest rate concessions, revised rate	7.60%	0.00%	7.60%	0.00%
Commercial | Automotive | Interest rate concessions | Pass
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Automotive | Interest rate concessions | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Automotive | Interest rate concessions | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					64
Commercial | Automotive | Interest rate concessions | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Automotive | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0	$ 0	$ 0
Interest rate concessions, initial rate	0.00%	0.00%	0.00%	0.00%
Interest rate concessions, revised rate	0.00%	0.00%	0.00%	0.00%
Commercial | Other
Financing Receivable, Troubled Debt Restructuring
Total	$ 29		$ 60	$ 108	100	108
Commercial | Other | Pass
Financing Receivable, Troubled Debt Restructuring
Total					39	53
Commercial | Other | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					29	0
Commercial | Other | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					32	55
Commercial | Other | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					0	0
Commercial | Other | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 0		$ 3	$ 0	4
Payment extensions, number of months extended/deferred	12 months		14 months	42 months
Commercial | Other | Payment deferrals | Pass
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Other | Payment deferrals | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Other | Payment deferrals | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					4
Commercial | Other | Payment deferrals | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Other | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	$ 29		$ 57	$ 108	82	108
Commercial | Other | Contractual maturity extensions | Pass
Financing Receivable, Troubled Debt Restructuring
Total					25	53
Commercial | Other | Contractual maturity extensions | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					29	0
Commercial | Other | Contractual maturity extensions | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					28	55
Commercial | Other | Contractual maturity extensions | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					0	$ 0
Commercial | Other | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0		0	0
Principal forgiveness, amount forgiven	0		0	0
Commercial | Other | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 0		$ 0	$ 0
Interest rate concessions, initial rate	0.00%		0.00%	0.00%
Interest rate concessions, revised rate	0.00%		0.00%	0.00%
Commercial | Other | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 0		$ 0	$ 0	14
Interest rate concessions, initial rate	0.00%		0.00%	0.00%
Interest rate concessions, revised rate	0.00%		0.00%	0.00%
Commercial | Other | Combination | Pass
Financing Receivable, Troubled Debt Restructuring
Total					14
Commercial | Other | Combination | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Other | Combination | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Other | Combination | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate
Financing Receivable, Troubled Debt Restructuring
Total	$ 19		$ 20		20
Commercial | Commercial real estate | Pass
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					19
Commercial | Commercial real estate | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					1
Commercial | Commercial real estate | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	0		0
Commercial | Commercial real estate | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	0		0
Commercial | Commercial real estate | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0		0
Principal forgiveness, amount forgiven	0		0
Commercial | Commercial real estate | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 19		$ 19		19
Interest rate concessions, initial rate	10.70%		10.70%
Interest rate concessions, revised rate	5.70%		5.70%
Commercial | Commercial real estate | Interest rate concessions | Pass
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate | Interest rate concessions | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate | Interest rate concessions | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					19
Commercial | Commercial real estate | Interest rate concessions | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 0		$ 1		1
Interest rate concessions, initial rate	0.00%		5.00%
Interest rate concessions, revised rate	0.00%		3.00%
Payment extensions, initial term			29 months
Payment extensions, revised term			34 months
Commercial | Commercial real estate | Combination | Pass
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate | Combination | Special mention
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate | Combination | Substandard
Financing Receivable, Troubled Debt Restructuring
Total					0
Commercial | Commercial real estate | Combination | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total					$ 1