Note 2 - Securities - Available-for-sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Total, amortized cost	$ 676,208	$ 680,998
Securities available for sale, gross unrealized gains	1,405	2,206
Securities available for sale, gross unrealized losses	(68,460)	(66,112)
Fair value	609,153	617,092
US Government Agencies Debt Securities [Member]
Total, amortized cost	438,662	442,496
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(52,953)	(52,000)
Fair value	385,709	390,496
Collateralized Mortgage-Backed Securities [Member]
Total, amortized cost	34,059	35,168
Securities available for sale, gross unrealized gains	10	20
Securities available for sale, gross unrealized losses	(6,287)	(5,715)
Fair value	27,782	29,473
Municipal General Obligation Bonds [Member]
Total, amortized cost	172,279	172,126
Securities available for sale, gross unrealized gains	1,244	1,924
Securities available for sale, gross unrealized losses	(6,891)	(6,190)
Fair value	166,632	167,860
Municipal Revenue Bonds [Member]
Total, amortized cost	30,708	30,708
Securities available for sale, gross unrealized gains	151	262
Securities available for sale, gross unrealized losses	(2,329)	(2,207)
Fair value	28,530	28,763
Other Debt and Equity Securities [Member]
Total, amortized cost	500	500
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	0	0
Fair value	$ 500	$ 500