Investment Securities - Additional Information (Details) - USD ($)			3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	$ 248,000,000	$ 227,000,000
Proceeds from sale of debt securities, available-for-sale			$ 0	$ 0
Investment securities	40,700,000,000	45,100,000,000	40,700,000,000
Securities received as collateral	$ 13,000,000	$ 16,000,000	$ 13,000,000
Investment securities available for sale | Government Contracts Concentration Risk | US Treasury and Agency securities
Debt Securities, Available-for-sale [Line Items]
Percentage of portfolio	96.00%	97.00%