Investment Securities - Additional Information (Details) - USD ($)			3 Months Ended		6 Months Ended
	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	$ 245,000,000	$ 227,000,000
Proceeds from sale of debt securities, available-for-sale			$ 0	$ 0	$ 0	$ 0
Investment securities	40,600,000,000	45,100,000,000	40,600,000,000		40,600,000,000
Securities received as collateral	$ 6,000,000	$ 16,000,000	$ 6,000,000		$ 6,000,000
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%