Note 6 - Fair Value Measurements and Fair Value of Financial Instruments - Quantitative Information About Significant Unobservable Inputs (Details) $ in Thousands	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Securities available-for-sale	$ 620,579	$ 617,162
Fair Value, Recurring [Member]
Securities available-for-sale	620,579	617,162
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	6,751	7,122
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale	125,670	132,705
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	125,670	132,705
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	$ 6,751	$ 7,122
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Valuation Technique, Discounted Cash Flow [Member] \| Measurement Input, Discount Rate [Member]
Securities available-for-sale, rate	0.048	0.043

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

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
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+ Details