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Note 3 - Investment Securities (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($) shares	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) shares	Sep. 30, 2024 USD ($)	Sep. 25, 2025 USD ($)	Dec. 31, 2024 USD ($)
Debt Securities, Trading	$ 1,411		$ 1,411			$ 3,309
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	126		126			131
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Allowance for Credit Loss, Recovery	0		0
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	0
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss					$ 1,700	2,000
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss					$ 900	1,300
Proceeds from Sale of Debt Securities, Available-for-Sale	0	$ 0	0	$ 0
Proceeds from Calls of Debt Securities, Available-for-Sale	800	0	19,800	0
Proceeds from Sale of Held-to-Maturity Securities	0	0	0	$ 0
Debt Securities, Held-to-Maturity, Nonaccrual	0		0			0
Debt Securities, Held-to-Maturity, Nonaccrual, Interest Income	0	$ 0
Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	862,572		862,572			962,272
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	259,351		259,351
Financial Asset, Past Due [Member]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	$ 0		$ 0			0
Preferred Class B [Member] | Visa [Member]
Investment Owned, Conversion Ratio	1.5549		1.5549
Investment Owned, Balance, Shares (in shares) | shares	6,924		6,924
Investment, Tax Basis, Cost	$ 0		$ 0			0
Preferred Class A [Member] | Visa [Member]
Investment Owned, Balance, Shares (in shares) | shares	10,766		10,766
Asset Pledged as Collateral [Member] | Deposits [Member]
Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	$ 368,700		$ 368,700			$ 340,200

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