Note 2 - Securities - Available-for-sale Securities (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Securities available for sale, amortized cost	$ 646,031,000	$ 597,463,000
Securities available for sale, gross unrealized gains	776,000	5,238,000
Securities available for sale, gross unrealized losses	(41,146,000)	(9,958,000)
Securities available for sale, fair value	605,661,000	592,743,000
US Government Agencies Debt Securities [Member]
Securities available for sale, amortized cost	442,500,000	398,874,000
Securities available for sale, gross unrealized gains	74,000	266,000
Securities available for sale, gross unrealized losses	(31,996,000)	(8,769,000)
Securities available for sale, fair value	410,578,000	390,371,000
Collateralized Mortgage-Backed Securities [Member]
Securities available for sale, amortized cost	40,215,000	41,906,000
Securities available for sale, gross unrealized gains	123,000	549,000
Securities available for sale, gross unrealized losses	(2,592,000)	(652,000)
Securities available for sale, fair value	37,746,000	41,803,000
Municipal General Obligation Bonds [Member]
Securities available for sale, amortized cost	138,916,000	133,894,000
Securities available for sale, gross unrealized gains	540,000	4,092,000
Securities available for sale, gross unrealized losses	(4,785,000)	(392,000)
Securities available for sale, fair value	134,671,000	137,594,000
Municipal Revenue Bonds [Member]
Securities available for sale, amortized cost	23,900,000	22,289,000
Securities available for sale, gross unrealized gains	39,000	331,000
Securities available for sale, gross unrealized losses	(1,773,000)	(145,000)
Securities available for sale, fair value	22,166,000	22,475,000
Other Debt and Equity Securities [Member]
Securities available for sale, amortized cost	500,000	500,000
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	0	0
Securities available for sale, fair value	$ 500,000	$ 500,000

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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