Loans and Card Member Receivables - Card Member Receivables (Details) - Card Member receivables - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 60,411	$ 57,613
Financing receivables, reserves for credit losses	174	229	$ 64	$ 267
Financing receivables, net	60,237	57,384
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	25,578	22,885
Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	19,286	19,629
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	15,547	15,099
Variable Interest Entity, Primary Beneficiary
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	4,587	5,193
Variable Interest Entity, Primary Beneficiary | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 4,600	$ 5,200