Loans and Card Member Receivables - Modifications that Subsequently Defaulted (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	$ 133	$ 157
Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	2	2
Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	112	128
Term Extension
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	20	27
Card Member loans | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	74	88
Card Member loans | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	37	40
Card Member loans | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Card Member loans | Interest Rate Reduction and Term Extension | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Card Member loans | Interest Rate Reduction and Term Extension | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Card Member loans | Interest Rate Reduction and Term Extension | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Card Member loans | Interest Rate Reduction | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	74	88
Card Member loans | Interest Rate Reduction | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	37	40
Card Member loans | Interest Rate Reduction | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Card Member receivables | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	6	10
Card Member receivables | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	13	17
Card Member receivables | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	1	0
Card Member receivables | Interest Rate Reduction and Term Extension | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Card Member receivables | Interest Rate Reduction and Term Extension | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Card Member receivables | Interest Rate Reduction and Term Extension | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Card Member receivables | Term Extension | Consumer
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	6	10
Card Member receivables | Term Extension | Small Business
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	13	17
Card Member receivables | Term Extension | Corporate
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	1	0
Other loans
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	2	2
Other loans | Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	2	2
Other loans | Interest Rate Reduction
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	0	0
Other loans | Term Extension
Financing Receivable, Modifications [Line Items]
Account balance, modified and subsequent default	$ 0	$ 0