Derivative Financial Instruments - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Derivative
Collateral held for derivative assets	$ 728,000,000		$ 728,000,000		$ 1,300,000,000
Valuation adjustments related to the credit risk associated with counterparties of customer accommodation derivative contracts	8,000,000		8,000,000		7,000,000
Amount of variation margin payment applied to derivative liability contracts	437,000,000		437,000,000		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	3,270,000,000		3,270,000,000		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			88 months
Deferred loss, net of tax, on cash flow hedges recorded in accumulated other comprehensive income	186,000,000		$ 186,000,000		372,000,000
Net deferred loss, net of tax, recorded in AOCI are expected to be reclassified into earnings	111,000,000		111,000,000
Interest rate contracts | Credit Risk
Derivative
Fair value of risk participation agreements	$ 5,000,000		$ 5,000,000		$ 6,000,000
Weighted-average remaining life			2 years 2 months 12 days