Finance Receivables and Loans, Net - Schedule of Financing Receivables, Nonaccrual Status (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2025	Dec. 31, 2024	Jun. 30, 2024	Dec. 31, 2023
Receivables [Abstract]
Financing receivable, nonaccrual, interest income	$ 4	$ 4	$ 11	$ 14
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	1,353		1,353		$ 1,359	$ 1,486	$ 1,215	$ 1,394
Financing receivable, nonaccrual, with no allowance	500		500			518
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	1,210		1,210		1,203	1,375	1,099	1,275
Financing receivable, nonaccrual, with no allowance	479		479			512
Consumer | Automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	1,140		1,140		1,134	1,231	978	1,129
Financing receivable, nonaccrual, with no allowance	426		426			476
Consumer | Consumer mortgage finance receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	70		70		69	54	41	54
Financing receivable, nonaccrual, with no allowance	53		53			36
Consumer | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	0		0		0	90	80	92
Financing receivable, nonaccrual, with no allowance	0		0			0
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	143		143		156	111	116	119
Financing receivable, nonaccrual, with no allowance	21		21			6
Commercial | Automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	9		9		38	15	18	18
Financing receivable, nonaccrual, with no allowance	9		9			0
Commercial | Consumer mortgage finance receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	10		10		20	2	2	3
Financing receivable, nonaccrual, with no allowance	8		8			2
Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	124		124		$ 98	94	$ 96	$ 98
Financing receivable, nonaccrual, with no allowance	$ 4		$ 4			$ 4