Note 3 - Securities - Amortized Cost and Fair Value of Investments in Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale, Amortized Cost	$ 577,834	$ 679,111
Securities available for sale, unrealized gains	4	17
Securities available for sale, unrealized losses	56,319	71,066
Securities available for sale, fair value	521,519	608,062
US Treasury Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	131,731	152,033
Securities available for sale, unrealized gains	0	0
Securities available for sale, unrealized losses	7,964	12,606
Securities available for sale, fair value	123,767	139,427
US Government-sponsored Enterprises Debt Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	76,702	90,363
Securities available for sale, unrealized gains	3	4
Securities available for sale, unrealized losses	4,472	7,019
Securities available for sale, fair value	72,233	83,348
Collateralized Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	292,590	336,393
Securities available for sale, unrealized gains	1	1
Securities available for sale, unrealized losses	35,827	42,301
Securities available for sale, fair value	256,764	294,093
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	45,999	69,023
Securities available for sale, unrealized gains	0	12
Securities available for sale, unrealized losses	3,577	5,312
Securities available for sale, fair value	42,422	63,723
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	30,812	31,299
Securities available for sale, unrealized gains	0	0
Securities available for sale, unrealized losses	4,479	3,828
Securities available for sale, fair value	$ 26,333	$ 27,471