Derivative Financial Instruments - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Derivative
Collateral held for derivative assets	$ 1,400,000,000		$ 1,400,000,000		$ 1,300,000,000
Valuation adjustments related to the credit risk associated with counterparties of customer accommodation derivative contracts	4,000,000		4,000,000		7,000,000
Amount of variation margin payment applied to derivative liability contracts	1,200,000,000		1,200,000,000		721,000,000
Gain or losses reclassified from AOCI into earnings associated with the discontinuance of cash flow hedges	0	$ 0	0	$ 0
Notional amount of the risk participations agreements	3,346,000,000		3,346,000,000		3,563,000,000
Total collateral
Derivative
Collateral held for derivative liabilities	1,200,000,000		$ 1,200,000,000		1,100,000,000
Interest rate contracts
Derivative
Maximum length of time of hedging exposure			91 months
Deferred loss, net of tax, on cash flow hedges recorded in accumulated other comprehensive income	659,000,000		$ 659,000,000		372,000,000
Net deferred loss, net of tax, recorded in AOCI are expected to be reclassified into earnings	289,000,000		289,000,000
Interest rate contracts | Credit Risk
Derivative
Fair value of risk participation agreements	$ 6,000,000		$ 6,000,000		$ 6,000,000
Weighted-average remaining life			2 years 4 months 24 days