Note 4 - Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Securities available-for-sale, amortized costs	$ 688,796	$ 697,786
Securities available-for-sale, gross unrealized gains	27	0
Securities available-for-sale, gross unrealized losses	83,627	79,185
Securities available-for-sale, fair values	605,196	618,601
US Government Agencies Debt Securities [Member]
Securities available-for-sale, amortized costs	353,018	353,904
Securities available-for-sale, gross unrealized gains	0	0
Securities available-for-sale, gross unrealized losses	44,205	42,060
Securities available-for-sale, fair values	308,813	311,844
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, amortized costs	178,435	179,507
Securities available-for-sale, gross unrealized gains	0	0
Securities available-for-sale, gross unrealized losses	32,433	29,614
Securities available-for-sale, fair values	146,002	149,893
Collateralized Mortgage-Backed Securities [Member]
Securities available-for-sale, amortized costs	149,839	156,875
Securities available-for-sale, gross unrealized gains	27	0
Securities available-for-sale, gross unrealized losses	6,120	6,724
Securities available-for-sale, fair values	143,746	150,151
Corporate Debt Securities [Member]
Securities available-for-sale, amortized costs	6,506	6,504
Securities available-for-sale, gross unrealized gains	0	0
Securities available-for-sale, gross unrealized losses	849	754
Securities available-for-sale, fair values	5,657	5,750
US Treasury Securities [Member]
Securities available-for-sale, amortized costs	998	996
Securities available-for-sale, gross unrealized gains	0	0
Securities available-for-sale, gross unrealized losses	20	33
Securities available-for-sale, fair values	$ 978	$ 963