Finance Receivables and Loans, Net (Loan Modifications) (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($) loan	Mar. 31, 2024 USD ($) loan	Dec. 31, 2023 USD ($)
Financing Receivable, Troubled Debt Restructuring
Trial modifications, term	3 months
Trial modifications, amount	$ 2		$ 2	$ 5
Total	$ 240	$ 131
Percentage of total	0.20%	0.10%
Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 62
Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	228	23
Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	1	2
Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	10	3
Combination
Financing Receivable, Troubled Debt Restructuring
Total	1	41
Consumer
Financing Receivable, Troubled Debt Restructuring
Total	107	62	333
Consumer | Current
Financing Receivable, Troubled Debt Restructuring
Total		53	272
Consumer | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		4	40
Consumer | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		2	11
Consumer | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		3	10
Consumer | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	0	0
Consumer | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	99	16
Consumer | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	1	2
Consumer | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	6	3
Consumer | Combination
Financing Receivable, Troubled Debt Restructuring
Total	1	41
Consumer | Automotive
Financing Receivable, Troubled Debt Restructuring
Total	100	$ 55	$ 315
Number of loans redefaulted | loan		12	481
Amortized cost of loans redefaulted		$ 1	$ 11
Consumer | Automotive | Current
Financing Receivable, Troubled Debt Restructuring
Total		50	259
Consumer | Automotive | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		3	39
Consumer | Automotive | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	10
Consumer | Automotive | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		2	7
Consumer | Automotive | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 0
Number of months extended/deferred	29 months	26 months
Consumer | Automotive | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	$ 99	$ 14	303
Consumer | Automotive | Contractual maturity extensions | Current
Financing Receivable, Troubled Debt Restructuring
Total		13	253
Consumer | Automotive | Contractual maturity extensions | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		1	38
Consumer | Automotive | Contractual maturity extensions | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	10
Consumer | Automotive | Contractual maturity extensions | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	2
Consumer | Automotive | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	1	2	12
Principal forgiveness, amount forgiven	0	1
Consumer | Automotive | Principal forgiveness | Current
Financing Receivable, Troubled Debt Restructuring
Total		0	6
Consumer | Automotive | Principal forgiveness | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	1
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		2	5
Consumer | Automotive | Interest rate concessions
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%
Consumer | Automotive | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 39
Interest rate concessions, initial rate	0.00%	10.40%
Interest rate concessions, revised rate	0.00%	9.70%
Payment extensions, initial term		74 months
Payment extensions, revised term		85 months
Consumer | Automotive | Combination | Current
Financing Receivable, Troubled Debt Restructuring
Total		$ 37
Consumer | Automotive | Combination | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		2
Consumer | Automotive | Combination | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0
Consumer | Automotive | Combination | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		0
Consumer | Consumer mortgage
Financing Receivable, Troubled Debt Restructuring
Total	$ 1	4	4
Consumer | Consumer mortgage | Current
Financing Receivable, Troubled Debt Restructuring
Total		2	4
Consumer | Consumer mortgage | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Consumer mortgage | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		2	0
Consumer | Consumer mortgage | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Consumer mortgage | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	0	$ 0
Number of months extended/deferred		159 months
Consumer | Consumer mortgage | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	0	$ 2
Consumer | Consumer mortgage | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0	0
Principal forgiveness, amount forgiven	0	0
Consumer | Consumer mortgage | Interest rate concessions
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%
Consumer | Consumer mortgage | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 1	$ 2
Interest rate concessions, initial rate	3.50%	4.90%
Interest rate concessions, revised rate	3.40%	3.90%
Payment extensions, initial term	355 months	314 months
Payment extensions, revised term	480 months	467 months
Consumer | Mortgage Finance
Financing Receivable, Troubled Debt Restructuring
Total		$ 4	2
Consumer | Mortgage Finance | Current
Financing Receivable, Troubled Debt Restructuring
Total		2	2
Consumer | Mortgage Finance | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Mortgage Finance | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		2	0
Consumer | Mortgage Finance | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Mortgage Finance | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total		$ 0
Number of months extended/deferred		159 months
Consumer | Mortgage Finance | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total		$ 2	1
Consumer | Mortgage Finance | Contractual maturity extensions | Current
Financing Receivable, Troubled Debt Restructuring
Total		2	1
Consumer | Mortgage Finance | Contractual maturity extensions | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Mortgage Finance | Contractual maturity extensions | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Mortgage Finance | Contractual maturity extensions | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Mortgage Finance | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total		0
Principal forgiveness, amount forgiven		0
Consumer | Mortgage Finance | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total		$ 0
Interest rate concessions, initial rate		0.00%
Interest rate concessions, revised rate		0.00%
Consumer | Mortgage Finance | Combination
Financing Receivable, Troubled Debt Restructuring
Total		$ 2	1
Interest rate concessions, initial rate		4.90%
Interest rate concessions, revised rate		3.90%
Payment extensions, initial term		314 months
Payment extensions, revised term		467 months
Consumer | Mortgage Finance | Combination | Current
Financing Receivable, Troubled Debt Restructuring
Total		$ 0	1
Consumer | Mortgage Finance | Combination | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Mortgage Finance | Combination | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		2	0
Consumer | Mortgage Finance | Combination | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	0
Consumer | Mortgage — Legacy
Financing Receivable, Troubled Debt Restructuring
Total	$ 1		2
Consumer | Mortgage — Legacy | Current
Financing Receivable, Troubled Debt Restructuring
Total			2
Consumer | Mortgage — Legacy | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Mortgage — Legacy | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Mortgage — Legacy | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Mortgage — Legacy | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	0
Consumer | Mortgage — Legacy | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	0		1
Consumer | Mortgage — Legacy | Contractual maturity extensions | Current
Financing Receivable, Troubled Debt Restructuring
Total			1
Consumer | Mortgage — Legacy | Contractual maturity extensions | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Mortgage — Legacy | Contractual maturity extensions | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Mortgage — Legacy | Contractual maturity extensions | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Mortgage — Legacy | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0
Principal forgiveness, amount forgiven	0
Consumer | Mortgage — Legacy | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 0
Interest rate concessions, initial rate	0.00%
Interest rate concessions, revised rate	0.00%
Consumer | Mortgage — Legacy | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 1		1
Interest rate concessions, initial rate	3.50%
Interest rate concessions, revised rate	3.40%
Payment extensions, initial term	355 months
Payment extensions, revised term	480 months
Consumer | Mortgage — Legacy | Combination | Current
Financing Receivable, Troubled Debt Restructuring
Total			1
Consumer | Mortgage — Legacy | Combination | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Mortgage — Legacy | Combination | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Mortgage — Legacy | Combination | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total			0
Consumer | Other
Financing Receivable, Troubled Debt Restructuring
Total	$ 6	3	14
Consumer | Other | Current
Financing Receivable, Troubled Debt Restructuring
Total		1	9
Consumer | Other | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		1	1
Consumer | Other | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	1
Consumer | Other | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		1	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	0
Principal forgiveness, amount forgiven	0	0
Consumer | Other | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 6	$ 3
Interest rate concessions, initial rate	30.50%	29.60%
Interest rate concessions, revised rate	10.10%	10.60%
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%
Consumer | Credit Card
Financing Receivable, Troubled Debt Restructuring
Total	$ 6	$ 3
Consumer | Credit Card | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	0	0
Consumer | Credit Card | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	0	0
Consumer | Credit Card | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0	0
Principal forgiveness, amount forgiven	0	0
Consumer | Credit Card | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 6	$ 3	14
Interest rate concessions, initial rate	30.50%	29.60%
Interest rate concessions, revised rate	10.10%	10.60%
Consumer | Credit Card | Interest rate concessions | Current
Financing Receivable, Troubled Debt Restructuring
Total		$ 1	9
Consumer | Credit Card | Interest rate concessions | 30–59 days past due
Financing Receivable, Troubled Debt Restructuring
Total		1	1
Consumer | Credit Card | Interest rate concessions | 60–89 days past due
Financing Receivable, Troubled Debt Restructuring
Total		0	1
Consumer | Credit Card | Interest rate concessions | 90 or more days past due
Financing Receivable, Troubled Debt Restructuring
Total		1	3
Consumer | Credit Card | 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	$ 133	$ 69	171
Commercial | Pass
Financing Receivable, Troubled Debt Restructuring
Total			107
Commercial | Special mention
Financing Receivable, Troubled Debt Restructuring
Total		7	0
Commercial | Substandard
Financing Receivable, Troubled Debt Restructuring
Total		34	64
Commercial | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total		28	0
Commercial | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 62
Number of months extended/deferred	41 months	12 months
Commercial | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	$ 129	$ 7
Commercial | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0	0
Principal forgiveness, amount forgiven	0	0
Commercial | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 4	$ 0
Interest rate concessions, initial rate	12.90%	0.00%
Interest rate concessions, revised rate	11.50%	0.00%
Commercial | 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 | Automotive
Financing Receivable, Troubled Debt Restructuring
Total	$ 4
Commercial | Automotive | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	0
Commercial | Automotive | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	0
Commercial | Automotive | Principal forgiveness
Financing Receivable, Troubled Debt Restructuring
Total	0
Principal forgiveness, amount forgiven	0
Commercial | Automotive | Interest rate concessions
Financing Receivable, Troubled Debt Restructuring
Total	$ 4		4
Interest rate concessions, initial rate	12.90%
Interest rate concessions, revised rate	11.50%
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			4
Commercial | Automotive | Interest rate concessions | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total			0
Commercial | Automotive | Combination
Financing Receivable, Troubled Debt Restructuring
Total	$ 0
Interest rate concessions, initial rate	0.00%
Interest rate concessions, revised rate	0.00%
Commercial | Other
Financing Receivable, Troubled Debt Restructuring
Total	$ 129	$ 69
Commercial | Other | Payment deferrals
Financing Receivable, Troubled Debt Restructuring
Total	$ 0	$ 62
Number of months extended/deferred	41 months	12 months
Commercial | Other | Payment deferrals | Special mention
Financing Receivable, Troubled Debt Restructuring
Total		$ 0
Commercial | Other | Payment deferrals | Substandard
Financing Receivable, Troubled Debt Restructuring
Total		34
Commercial | Other | Payment deferrals | Doubtful
Financing Receivable, Troubled Debt Restructuring
Total		28
Commercial | Other | Contractual maturity extensions
Financing Receivable, Troubled Debt Restructuring
Total	$ 129	7	167
Commercial | Other | Contractual maturity extensions | Pass
Financing Receivable, Troubled Debt Restructuring
Total			107
Commercial | Other | Contractual maturity extensions | Special mention
Financing Receivable, Troubled Debt Restructuring
Total		7	0
Commercial | Other | Contractual maturity extensions | Substandard
Financing Receivable, Troubled Debt Restructuring
Total		0	60
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
Principal forgiveness, amount forgiven	0	0
Commercial | Other | Interest rate concessions
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 | 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%