Derivative Financial Instruments - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Derivative
Collateral held for derivative assets	$ 513,000,000		$ 513,000,000		$ 947,000,000
Amount of variation margin payment applied to derivative asset contracts	302,000,000		302,000,000		403,000,000
Valuation adjustments related to the credit risk associated with counterparties of customer accommodation derivative contracts	7,000,000		7,000,000		4,000,000
Amount of variation margin payment applied to derivative liability contracts	381,000,000		381,000,000		1,200,000,000
Gain or losses reclassified from AOCI into earnings associated with the discontinuance of cash flow hedges	0	$ 0	0	$ 0
Total collateral
Derivative
Collateral held for derivative liabilities	988,000,000		$ 988,000,000		1,100,000,000
Interest rate contracts
Derivative
Maximum length of time of hedging exposure			76 months
Deferred loss, net of tax, on cash flow hedges recorded in accumulated other comprehensive income	257,000,000		$ 257,000,000		654,000,000
Net deferred loss, net of tax, recorded in AOCI are expected to be reclassified into earnings	171,000,000		171,000,000
Interest rate contracts | Credit Risk
Derivative
Notional amount of the risk participations agreements	3,000,000,000.0		3,000,000,000.0		3,200,000,000
Fair value of risk participation agreements	$ 4,000,000		$ 4,000,000		$ 5,000,000