Loans and Card Member Receivables - Card Member Receivables (Details) - Card Member receivables - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 59,411	$ 60,411
Financing receivables, reserves for credit losses	171	174	$ 229	$ 64
Financing receivables, net	59,240	60,237
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	25,431	25,578
Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	18,619	19,286
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	15,361	15,547
Variable Interest Entity, Primary Beneficiary
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	3,927	4,587
Variable Interest Entity, Primary Beneficiary | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 3,900	$ 4,600