Card Balances and Other Loans - Modifications Subsequently Defaulted (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	$ 91	$ 74	$ 129	$ 117
Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	2	1	3	2
Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	71	59	104	96
Term Extension
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	18	14	22	19
Card Balances | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	55	45	78	71
Card Balances | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	32	28	45	44
Card Balances | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	1	0	2	0
Card Balances | Interest Rate Reduction and Term Extension | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0	0	0
Card Balances | Interest Rate Reduction and Term Extension | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0	0	0
Card Balances | Interest Rate Reduction and Term Extension | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0	0	0
Card Balances | Interest Rate Reduction | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	47	40	69	65
Card Balances | Interest Rate Reduction | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	24	19	35	31
Card Balances | Interest Rate Reduction | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0	0	0
Card Balances | Term Extension | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	8	5	10	6
Card Balances | Term Extension | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	8	9	10	13
Card Balances | Term Extension | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	1	0	2	0
Other Loans
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	2	1	3	2
Other Loans | Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	2	1	3	2
Other Loans | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0	0	0
Other Loans | Term Extension
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	$ 0	$ 0	$ 0	$ 0