Investment Securities - Additional Information (Details) - USD ($)	6 Months Ended
Jun. 30, 2026	Dec. 31, 2025
Additional disclosures
Other investment securities	$ 0
Other Assets
Additional disclosures
Accrued interest receivable for investment securities	42,000,000	$ 38,900,000
Asset Pledged as Collateral
Additional disclosures
Investment securities market value	5,100,000,000	5,200,000,000
Carrying value of public fund deposits	5,400,000,000	5,500,000,000
Asset Pledged as Collateral \| Public Funds Deposits
Additional disclosures
Carrying value of public fund deposits	5,300,000,000	5,200,000,000
Asset Pledged as Collateral \| FHLB Advances
Additional disclosures
Carrying value of public fund deposits	23,800,000	182,200,000
Asset Pledged as Collateral \| Interest rate swap
Additional disclosures
Carrying value of public fund deposits	$ 78,400,000	$ 83,300,000

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Interest, dividends, rents, ancillary and other revenues earned but not yet received by the entity on its investments.

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Amount of impairment loss on investment in equity security without readily determinable fair value.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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