Loans and Card Member Receivables - Performance (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Current
Financing Receivable, Modifications [Line Items]
Account balances	$ 2,950	$ 2,863
30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Account balances	223	220
90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Account balances	82	89
Card Member loans | Current | Consumer
Financing Receivable, Modifications [Line Items]
Account balances	1,709	1,615
Card Member loans | Current | Small Business
Financing Receivable, Modifications [Line Items]
Account balances	656	568
Card Member loans | Current | Corporate
Financing Receivable, Modifications [Line Items]
Account balances	0	0
Card Member loans | 30-89 Days Past Due | Consumer
Financing Receivable, Modifications [Line Items]
Account balances	116	110
Card Member loans | 30-89 Days Past Due | Small Business
Financing Receivable, Modifications [Line Items]
Account balances	60	56
Card Member loans | 30-89 Days Past Due | Corporate
Financing Receivable, Modifications [Line Items]
Account balances	0	0
Card Member loans | 90+ Days Past Due | Consumer
Financing Receivable, Modifications [Line Items]
Account balances	43	45
Card Member loans | 90+ Days Past Due | Small Business
Financing Receivable, Modifications [Line Items]
Account balances	22	22
Card Member loans | 90+ Days Past Due | Corporate
Financing Receivable, Modifications [Line Items]
Account balances	0	0
Card Member receivables | Current | Consumer
Financing Receivable, Modifications [Line Items]
Account balances	186	234
Card Member receivables | Current | Small Business
Financing Receivable, Modifications [Line Items]
Account balances	303	357
Card Member receivables | Current | Corporate
Financing Receivable, Modifications [Line Items]
Account balances	11	10
Card Member receivables | 30-89 Days Past Due | Consumer
Financing Receivable, Modifications [Line Items]
Account balances	12	16
Card Member receivables | 30-89 Days Past Due | Small Business
Financing Receivable, Modifications [Line Items]
Account balances	27	31
Card Member receivables | 30-89 Days Past Due | Corporate
Financing Receivable, Modifications [Line Items]
Account balances	3	2
Card Member receivables | 90+ Days Past Due | Consumer
Financing Receivable, Modifications [Line Items]
Account balances	5	6
Card Member receivables | 90+ Days Past Due | Small Business
Financing Receivable, Modifications [Line Items]
Account balances	9	13
Card Member receivables | 90+ Days Past Due | Corporate
Financing Receivable, Modifications [Line Items]
Account balances	2	1
Other loans | Current
Financing Receivable, Modifications [Line Items]
Account balances	83	79
Other loans | 30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Account balances	5	5
Other loans | 90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Account balances	$ 2	$ 2