Note 2 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Securities available for sale, continuous unrealized loss position, less than 12 months	$ 21,735	$ 2,729
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	202	14
Securities available for sale, continuous unrealized loss position, 12 months or more	534,348	546,018
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	68,258	66,098
Securities available for sale, continuous unrealized loss position	556,083	548,747
Securities available for sale, continuous unrealized loss position, unrealized loss	68,460	66,112
US Government Agencies Debt 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	385,709	390,496
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	52,953	52,000
Securities available for sale, continuous unrealized loss position	385,709	390,496
Securities available for sale, continuous unrealized loss position, unrealized loss	52,953	52,000
Collateralized Mortgage-Backed Securities [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	201	114
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	3	0
Securities available for sale, continuous unrealized loss position, 12 months or more	27,089	28,749
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	6,284	5,715
Securities available for sale, continuous unrealized loss position	27,290	28,863
Securities available for sale, continuous unrealized loss position, unrealized loss	6,287	5,715
Municipal General Obligation Bonds [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	20,393	1,109
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	189	6
Securities available for sale, continuous unrealized loss position, 12 months or more	100,489	106,171
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	6,702	6,184
Securities available for sale, continuous unrealized loss position	120,882	107,280
Securities available for sale, continuous unrealized loss position, unrealized loss	6,891	6,190
Municipal Revenue Bonds [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	1,141	1,506
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	10	8
Securities available for sale, continuous unrealized loss position, 12 months or more	21,061	20,602
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	2,319	2,199
Securities available for sale, continuous unrealized loss position	22,202	22,108
Securities available for sale, continuous unrealized loss position, unrealized loss	2,329	2,207
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