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Loans - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) segment	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of portfolio segments | segment			3
Accrued interest receivable	$ 3,000		$ 3,000		$ 2,200
Net loans held for investment	415,424		415,424		311,517
Federal Home Loan banks
Financing Receivable, Allowance for Credit Loss [Line Items]
Net loans held for investment	6,500		6,500		6,700
Remaining borrowing capacity	34,100		34,100		35,100
Federal Reserve Discount Window
Financing Receivable, Allowance for Credit Loss [Line Items]
Net loans held for investment	81,700		81,700		80,200
Remaining borrowing capacity	47,100		47,100		$ 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	$ 263	$ 205	$ 404	$ 321

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