Loans - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)	Dec. 31, 2023 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	299,774		305,176
Federal Home Loan banks
Financing Receivable, Allowance for Credit Loss [Line Items]
Net loans held for investment	7,400		7,400
Remaining borrowing capacity	36,700		32,100
Federal Reserve Discount Window
Financing Receivable, Allowance for Credit Loss [Line Items]
Net loans held for investment	74,100		78,300
Remaining borrowing capacity	38,800		$ 41,400
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	$ 116	$ 183