Note 2 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Securities available for sale, continuous unrealized loss position, less than 12 months	$ 2,729	$ 193,930
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	14	17,438
Securities available for sale, continuous unrealized loss position, 12 months or more	546,018	379,216
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	66,098	65,843
Securities available for sale, continuous unrealized loss position	548,747	573,146
Securities available for sale, continuous unrealized loss position, unrealized loss	66,112	83,281
US Government Agencies Debt Securities [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	0	53,019
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	0	5,713
Securities available for sale, continuous unrealized loss position, 12 months or more	390,496	335,725
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	52,000	59,379
Securities available for sale, continuous unrealized loss position	390,496	388,744
Securities available for sale, continuous unrealized loss position, unrealized loss	52,000	65,092
Collateralized Mortgage-Backed Securities [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	114	31,127
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	0	6,068
Securities available for sale, continuous unrealized loss position, 12 months or more	28,749	12
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	5,715	0
Securities available for sale, continuous unrealized loss position	28,863	31,139
Securities available for sale, continuous unrealized loss position, unrealized loss	5,715	6,068
Municipal General Obligation Bonds [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	1,109	97,252
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	6	4,516
Securities available for sale, continuous unrealized loss position, 12 months or more	106,171	32,870
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	6,184	4,542
Securities available for sale, continuous unrealized loss position	107,280	130,122
Securities available for sale, continuous unrealized loss position, unrealized loss	6,190	9,058
Municipal Revenue Bonds [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	1,506	12,532
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	8	1,141
Securities available for sale, continuous unrealized loss position, 12 months or more	20,602	10,609
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	2,199	1,922
Securities available for sale, continuous unrealized loss position	22,108	23,141
Securities available for sale, continuous unrealized loss position, unrealized loss	2,207	3,063
Other Debt and Equity Securities [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	0	0
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	0	0
Securities available for sale, continuous unrealized loss position, 12 months or more	0	0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	0	0
Securities available for sale, continuous unrealized loss position	0	0
Securities available for sale, continuous unrealized loss position, unrealized loss	$ 0	$ 0