Card Balances and Other Loans - Summary (Details) - USD ($) $ in Millions	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Card Balances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 218,054		$ 213,863
Financing receivable, reserves for credit losses	5,866	$ 6,065	6,089	$ 5,960	$ 5,740	$ 5,850
Financing receivables, net	212,188		207,774
Card Balances \| Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	144,974		144,324
Card Balances \| Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	56,172		53,632
Card Balances \| Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	16,908		15,907
Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	11,428		10,928
Financing receivable, reserves for credit losses	312	$ 314	323	$ 272	$ 244	$ 194
Financing receivables, net	11,115		10,605
Variable Interest Entity, Primary Beneficiary \| Card Balances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	32,167		33,378
Variable Interest Entity, Primary Beneficiary \| Card Balances \| Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 32,200		$ 33,400