Note 3 - Investment Securities (Details Textual) $ in Thousands	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	$ 0	$ 0
Debt Securities, Available-for-Sale, Restricted	$ 295,700	$ 259,800
Number Of Holdings Greater Than 10 Percent Of Stockholders Equity	0	0
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0	$ 0
Debt Securities, Available-for-Sale, Unrealized Loss Position	542,830	553,283
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	67,463	74,114
Commercial Mortgage-Backed Securities [Member]
Financial Instruments, Owned, at Fair Value	72,900
Equipment Finance Loans Backed Securities [Member]
Financial Instruments, Owned, at Fair Value	21,500
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position	130,206	131,887
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	17,573	16,374
Passthrough Mortgage Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position	127,762	128,555
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	25,368	29,357
Collateralized Debt Obligations [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position	92,361	96,092
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	19,365	21,550
Company Agency Obligations [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position	77,636	83,439
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	1,022	1,143
Corporate Bond Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position	114,865	113,310
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	$ 4,135	$ 5,690
Number Of Financial Institutions	6
Debt Securities, Available-for-Sale, Term (Year)	10 years

The number of financial institutions.

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The number of holdings of any one issuer in an amount greater than 10% of stockholders' equity.

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Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Period between issuance and maturity of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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The aggregate fair value as of the balance sheet date of financial instruments and other positions owned by the entity including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. Includes both pledged and unpledged holdings.

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Amount, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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