Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Income Taxes [Line Items]
Federal statutory tax rate			21.00%
Income tax expense	$ 10,848,000	$ 12,095,000	$ 34,291,000	$ 34,359,000
Effective tax rates on pre-tax income	17.96%	16.93%	18.31%	16.35%
Initial capital contribution commitment			$ 5,500,000
Initial contribution included in other assets			539,000	$ 131,000	$ 131,000
Leveraged loan, invest in other borrowings	$ 21,053,000		$ 21,053,000
NMTC Investments [Member]
Income Taxes [Line Items]
Tax Benefit Percent of Qualified Investments			0.39
Investment related liabilities	26,009,000	$ 29,000,000	$ 26,009,000	29,000,000	26,825,000
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