Loans - Additional Information (Details) $ in Millions	3 Months Ended
Mar. 31, 2025 USD ($) segment	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of portfolio segments \| segment	3
Accrued interest receivable	$ 2,200		$ 2,200
Net loans held for investment	307,699		311,517
Federal Home Loan banks
Financing Receivable, Allowance for Credit Loss [Line Items]
Net loans held for investment	6,900		6,700
Remaining borrowing capacity	34,900		35,100
Federal Reserve Discount Window
Financing Receivable, Allowance for Credit Loss [Line Items]
Net loans held for investment	75,900		80,200
Remaining borrowing capacity	44,400		$ 46,700
Domestic credit card: \| Domestic Credit Card and Commercial Banking Portfolios
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans converted to term during period	$ 141	$ 116

Amount, before allowance for credit loss, of accrued interest on financing receivable.

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