Loans - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) segment	Jun. 30, 2023 USD ($)	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		$ 2,200
Net loans held for investment	301,537		301,537		305,176
Federal Home Loan banks
Financing Receivable, Allowance for Credit Loss [Line Items]
Net loans held for investment	7,300		7,300		7,400
Remaining borrowing capacity	36,900		36,900		32,100
Federal Reserve Discount Window
Financing Receivable, Allowance for Credit Loss [Line Items]
Net loans held for investment	83,300		83,300		78,300
Remaining borrowing capacity	41,100		41,100		$ 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	$ 205	$ 159	$ 321	$ 342