Note 15 - Comprehensive Income - Accumulated Other Comprehensive (Loss) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Balance	$ 1,216,620	$ 1,178,751	$ 1,124,212	$ 915,310
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member]
Balance	(57,835)	(61,775)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Balance	24,810	32,360
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(2,084)	(2,949)
AOCI Attributable to Parent [Member]
Balance	$ (35,109)	$ (32,364)	$ (1,404)	$ 2,797