Loans and Card Member Receivables - Performance (Details 4) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances		$ 1,733
Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 1,328
30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	147
90+ Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	38
Card Member Loans | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances		781
Card Member Loans | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances		267
Card Member Loans | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances		0
Card Member Loans | Current | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	579
Card Member Loans | Current | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	236
Card Member Loans | Current | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	0
Card Member Loans | 30-89 Days Past Due | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	47
Card Member Loans | 30-89 Days Past Due | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	33
Card Member Loans | 30-89 Days Past Due | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	0
Card Member Loans | 90+ Days Past Due | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	16
Card Member Loans | 90+ Days Past Due | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	8
Card Member Loans | 90+ Days Past Due | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	0
Card Member Receivables | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances		257
Card Member Receivables | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances		403
Card Member Receivables | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances		6
Card Member Receivables | Current | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	182
Card Member Receivables | Current | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	293
Card Member Receivables | Current | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	13
Card Member Receivables | 30-89 Days Past Due | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	14
Card Member Receivables | 30-89 Days Past Due | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	50
Card Member Receivables | 30-89 Days Past Due | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	1
Card Member Receivables | 90+ Days Past Due | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	4
Card Member Receivables | 90+ Days Past Due | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	9
Card Member Receivables | 90+ Days Past Due | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	1
Other Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances		$ 19
Other Loans | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	25
Other Loans | 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	2
Other Loans | 90+ Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 0