Card Balances and Other Loans - Summary (Details) - USD ($) $ in Millions	Sep. 30, 2026	Jun. 30, 2026	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024
Card Balances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 221,074		$ 213,863
Financing receivable, reserves for credit losses	5,634	$ 5,866	6,089	$ 6,068	$ 5,960	$ 5,850
Financing receivables, net	215,440		207,774
Card Balances | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	145,733		144,324
Card Balances | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	57,315		53,632
Card Balances | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	18,026		15,907
Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	12,079		10,928
Financing receivable, reserves for credit losses	335	$ 312	323	$ 287	$ 272	$ 194
Financing receivables, net	11,744		10,605
Variable Interest Entity, Primary Beneficiary | Card Balances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	32,063		33,378
Variable Interest Entity, Primary Beneficiary | Card Balances | Consumer and Corporate Borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 32,100		$ 33,400