Loans and Card Member Receivables - Performance (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Modifications [Line Items]
Account Balances		$ 1,733	$ 1,332
Current
Financing Receivable, Modifications [Line Items]
Account Balances	$ 2,785
30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Account Balances	231
90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Account Balances	73
Card Member loans | Consumer
Financing Receivable, Modifications [Line Items]
Account Balances		781	708
Card Member loans | Small Business
Financing Receivable, Modifications [Line Items]
Account Balances		267	176
Card Member loans | Corporate
Financing Receivable, Modifications [Line Items]
Account Balances		0	0
Card Member loans | Current | Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	1,433
Card Member loans | Current | Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	489
Card Member loans | Current | Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	0
Card Member loans | 30-89 Days Past Due | Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	103
Card Member loans | 30-89 Days Past Due | Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	45
Card Member loans | 30-89 Days Past Due | Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	0
Card Member loans | 90+ Days Past Due | Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	36
Card Member loans | 90+ Days Past Due | Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	16
Card Member loans | 90+ Days Past Due | Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	0
Card Member receivables | Consumer
Financing Receivable, Modifications [Line Items]
Account Balances		257	133
Card Member receivables | Small Business
Financing Receivable, Modifications [Line Items]
Account Balances		403	247
Card Member receivables | Corporate
Financing Receivable, Modifications [Line Items]
Account Balances		6	1
Card Member receivables | Current | Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	314
Card Member receivables | Current | Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	479
Card Member receivables | Current | Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	11
Card Member receivables | 30-89 Days Past Due | Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	25
Card Member receivables | 30-89 Days Past Due | Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	52
Card Member receivables | 30-89 Days Past Due | Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	2
Card Member receivables | 90+ Days Past Due | Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	7
Card Member receivables | 90+ Days Past Due | Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	12
Card Member receivables | 90+ Days Past Due | Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	0
Other loans
Financing Receivable, Modifications [Line Items]
Account Balances		$ 19	$ 67
Other loans | Current
Financing Receivable, Modifications [Line Items]
Account Balances	59
Other loans | 30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Account Balances	4
Other loans | 90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Account Balances	$ 2