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Note 14 - Commitments and Contingencies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2035	Dec. 31, 2025	Dec. 31, 2024
Financing Receivable, before Allowance for Credit Loss	$ 1,547,551,000
Municipal Bonds [Member]
Investments	87,800,000	$ 98,100,000
US States and Political Subdivisions Debt Securities [Member]
Investments	$ 88,700,000	$ 87,300,000
Credit Concentration Risk [Member] \| Loans Receivable [Member] \| Loans Secured by Real Estate [Member]
Concentration Risk, Percentage	80.00%	79.80%
Investment Concentration Risk [Member] \| Investments [Member] \| Municipal Bonds [Member]
Concentration Risk, Percentage	28.40%	29.00%
Investment Concentration Risk [Member] \| Investments [Member] \| US States and Political Subdivisions Debt Securities [Member]
Concentration Risk, Percentage	28.70%	25.80%
Real Estate Loan [Member]
Financing Receivable, before Allowance for Credit Loss	$ 1,330,000,000	$ 1,240,000,000
Low Income Housing Tax Credit Investments [Member]
Amortization Method Qualified Affordable Housing Project Investments	4,700,000	4,900,000
Affordable Housing Tax Credits and Other Tax Benefits, Amount	194,000	77,000
Amortization Method Qualified Affordable Housing Project Investments, Amortization	165,000	66,000
Qualified Affordable Housing Project Investments, Commitment	4,400,000	4,700,000
Affordable Housing Project Investment, Write-down, Amount	$ 0	$ 0
Low Income Housing Tax Credit Investments [Member] \| Forecast [Member]
Qualified Affordable Housing Project Investments, Commitment			$ 291,000	$ 748,000,000,000	$ 3,400,000