Loans and Card Member Receivables - Card Member and other Loans (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Card Member loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 125,995	$ 107,964
Financing receivables, reserves for credit losses	5,118	3,747	$ 3,305	$ 5,344
Financing receivables, net	120,877	104,217
Card Member loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	98,111	84,964
Card Member loans | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	27,833	22,947
Card Member loans | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	51	53
Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, reserves for credit losses	126	59
Financing receivables, net	6,960	5,357
Variable Interest Entity, Primary Beneficiary | Card Member loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	28,590	28,461
Variable Interest Entity, Primary Beneficiary | Card Member loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 28,600	$ 28,500