Note 7 - Fair Value Measurements and Fair Value of Financial Instruments - Quantitative Information About Significant Unobservable Inputs (Details) $ in Thousands	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)
Securities available-for-sale, fair value	$ 1,196,384	$ 1,250,938
Fair Value, Recurring [Member]
Securities available-for-sale, fair value	1,196,384	1,250,938
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale, fair value	6,378	6,512
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, fair value	204,563	212,409
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale, fair value	204,563	212,409
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale, fair value	$ 6,378	$ 6,512
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, input	0.047	0.046