Note 2 - Securities - Securities in a Continuous Loss Position (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Securities available for sale, continuous unrealized loss position, less than 12 months	$ 303,956,000	$ 351,062,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	26,292,000	6,455,000
Securities available for sale, continuous unrealized loss position, 12 months or more	265,186,000	110,491,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	34,311,000	3,503,000
Securities available for sale, continuous unrealized loss position	569,142,000	461,553,000
Securities available for sale, continuous unrealized loss position, unrealized loss	60,603,000	9,958,000
US Government Agencies Debt Securities [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	176,893,000	274,287,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	17,028,000	5,274,000
Securities available for sale, continuous unrealized loss position, 12 months or more	230,442,000	110,053,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	29,149,000	3,495,000
Securities available for sale, continuous unrealized loss position	407,335,000	384,340,000
Securities available for sale, continuous unrealized loss position, unrealized loss	46,177,000	8,769,000
Collateralized Mortgage-Backed Securities [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	23,935,000	23,184,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	2,259,000	652,000
Securities available for sale, continuous unrealized loss position, 12 months or more	11,372,000	24,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	2,109,000	0
Securities available for sale, continuous unrealized loss position	35,307,000	23,208,000
Securities available for sale, continuous unrealized loss position, unrealized loss	4,368,000	652,000
Municipal General Obligation Bonds [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	90,305,000	40,748,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	5,551,000	392,000
Securities available for sale, continuous unrealized loss position, 12 months or more	16,284,000	0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	1,968,000	0
Securities available for sale, continuous unrealized loss position	106,589,000	40,748,000
Securities available for sale, continuous unrealized loss position, unrealized loss	7,519,000	392,000
Municipal Revenue Bonds [Member]
Securities available for sale, continuous unrealized loss position, less than 12 months	12,823,000	12,843,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	1,454,000	137,000
Securities available for sale, continuous unrealized loss position, 12 months or more	7,088,000	414,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	1,085,000	8,000
Securities available for sale, continuous unrealized loss position	19,911,000	13,257,000
Securities available for sale, continuous unrealized loss position, unrealized loss	$ 2,539,000	$ 145,000