Finance Receivables and Loans, Net - Schedule of Financing Receivables, Nonaccrual Status (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	$ 1,490		$ 1,490		$ 1,215	$ 1,394	$ 1,404	$ 1,454
Financing receivable, nonaccrual, with no allowance	606		606			585
Financing receivable, nonaccrual, interest income	4	$ 4	14	$ 11
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	1,334		1,334		1,099	1,275	1,216	1,292
Financing receivable, nonaccrual, with no allowance	559		559			564
Consumer | Automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	1,204		1,204		978	1,129	1,098	1,187
Financing receivable, nonaccrual, with no allowance	525		525			531
Consumer | Consumer mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	46		46		41	54	52	49
Financing receivable, nonaccrual, with no allowance	34		34			33
Consumer | Mortgage Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	37		37		32	41	38	34
Financing receivable, nonaccrual, with no allowance	25		25			21
Consumer | Mortgage — Legacy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	9		9		9	13	14	15
Financing receivable, nonaccrual, with no allowance	9		9			12
Consumer | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	84		84		80	92	66	56
Financing receivable, nonaccrual, with no allowance	0		0			0
Consumer | Personal Lending
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status						0	11	13
Financing receivable, nonaccrual, with no allowance						0
Consumer | Credit Card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	84		84		80	92	55	43
Financing receivable, nonaccrual, with no allowance	0		0			0
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	156		156		116	119	188	162
Financing receivable, nonaccrual, with no allowance	47		47			21
Commercial | Automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	51		51		18	18	24	5
Financing receivable, nonaccrual, with no allowance	33		33			13
Commercial | Consumer mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	10		10		2	3	3	0
Financing receivable, nonaccrual, with no allowance	10		10			3
Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, recorded investment, nonaccrual status	95		95		$ 96	98	$ 161	$ 157
Financing receivable, nonaccrual, with no allowance	$ 4		$ 4			$ 5