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Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Income Taxes [Line Items]
Federal statutory tax rate			21.00%
Income tax expense	$ 10,897,000	$ 12,028,000	$ 39,785,000	$ 34,664,000
Effective tax rates on pre-tax income	17.25%	17.86%	18.08%	17.70%
Initial contribution included in other assets			$ 5,855,000	$ 2,091,000	$ 3,925,000
Additional Contribution Of Property			5,000,000		7,000,000
Leveraged loan, invest in other borrowings	$ 21,053,000		21,053,000
Maximum [Member]
Income Taxes [Line Items]
Initial contribution included in other assets			$ 5,500,000
NMTC Investments [Member]
Income Taxes [Line Items]
Tax Benefit Percent of Qualified Investments			0.39
Investment related liabilities	23,454,000	$ 24,759,000	$ 23,454,000	24,759,000	24,433,000
FFB Paris Investment Fund, LLC [Member]
Income Taxes [Line Items]
Loan investment	18,000,000	18,000,000	18,000,000	18,000,000	18,000,000
Leveraged loan, invest in other borrowings	$ 21,053,000	$ 21,053,000	$ 21,053,000	$ 21,053,000	$ 21,053,000

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