Finance Receivables - Schedule of Net Finance Receivables by Type (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	$ 23,531	$ 23,207
Unearned fees	(283)	(271)
Accrued finance charges and fees	373	378
Deferred origination costs	249	240
Total	23,870	23,554
Personal Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	22,789	22,575
Unearned fees	(283)	(271)
Accrued finance charges and fees	373	378
Deferred origination costs	239	229
Total	23,118	22,911
Personal Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	20,506	20,514
Unearned fees	(244)	(239)
Accrued finance charges and fees	349	356
Deferred origination costs	203	202
Total	20,814	20,833
Auto Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	2,283	2,061
Unearned fees	(39)	(32)
Accrued finance charges and fees	24	22
Deferred origination costs	36	27
Total	2,304	2,078
Credit Cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	742	632
Unearned fees	0	0
Accrued finance charges and fees	0	0
Deferred origination costs	10	11
Total	$ 752	$ 643