Note 3 - Securities - Amortized Cost and Fair Value of Investments in Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale, Amortized Cost	$ 679,111	$ 694,639
Securities available for sale, unrealized gains	17	5,086
Securities available for sale, unrealized losses	71,066	7,258
Securities available for sale, fair value	608,062	692,467
US Treasury Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	152,033	150,751
Securities available for sale, unrealized gains	0	0
Securities available for sale, unrealized losses	12,606	1,174
Securities available for sale, fair value	139,427	149,577
US Government-sponsored Enterprises Debt Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	90,363	104,518
Securities available for sale, unrealized gains	4	993
Securities available for sale, unrealized losses	7,019	931
Securities available for sale, fair value	83,348	104,580
Collateralized Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	336,393	357,981
Securities available for sale, unrealized gains	1	2,854
Securities available for sale, unrealized losses	42,301	4,525
Securities available for sale, fair value	294,093	356,310
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	69,023	65,939
Securities available for sale, unrealized gains	12	1,021
Securities available for sale, unrealized losses	5,312	488
Securities available for sale, fair value	63,723	66,472
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost	31,299	15,450
Securities available for sale, unrealized gains	0	218
Securities available for sale, unrealized losses	3,828	140
Securities available for sale, fair value	$ 27,471	$ 15,528