Note 2 - Securities - Securities in a Continuous Loss Position (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Securities available for sale, continuous unrealized loss position, less than 12 months	$ 264,079,000	$ 351,062,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	32,907,000	6,455,000
Securities available for sale, continuous unrealized loss position, 12 months or more	310,224,000	110,491,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	58,862,000	3,503,000
Securities available for sale, continuous unrealized loss position	574,303,000	461,553,000
Securities available for sale, continuous unrealized loss position, unrealized loss	91,769,000	9,958,000
US Government Agencies Debt Securities [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	110,145,000	274,287,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	16,096,000	5,274,000
Securities available for sale, continuous unrealized loss position, 12 months or more	275,311,000	110,053,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	52,123,000	3,495,000
Securities available for sale, continuous unrealized loss position	385,456,000	384,340,000
Securities available for sale, continuous unrealized loss position, unrealized loss	68,219,000	8,769,000
Collateralized Mortgage-Backed Securities [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	31,918,000	23,184,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	6,365,000	652,000
Securities available for sale, continuous unrealized loss position, 12 months or more	13,000	24,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	1,000	0
Securities available for sale, continuous unrealized loss position	31,931,000	23,208,000
Securities available for sale, continuous unrealized loss position, unrealized loss	6,366,000	652,000
Municipal General Obligation Bonds [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	108,512,000	40,748,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	8,687,000	392,000
Securities available for sale, continuous unrealized loss position, 12 months or more	26,039,000	0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	4,617,000	0
Securities available for sale, continuous unrealized loss position	134,551,000	40,748,000
Securities available for sale, continuous unrealized loss position, unrealized loss	13,304,000	392,000
Municipal Revenue Bonds [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	13,504,000	12,843,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	1,759,000	137,000
Securities available for sale, continuous unrealized loss position, 12 months or more	8,861,000	414,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	2,121,000	8,000
Securities available for sale, continuous unrealized loss position	22,365,000	13,257,000
Securities available for sale, continuous unrealized loss position, unrealized loss	$ 3,880,000	$ 145,000