Note 2 - Securities - Available-for-sale Securities (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Amortized cost	$ 380,403,000	$ 329,979,000
Securities available for sale, gross unrealized gains	7,843,000	5,930,000
Securities available for sale, gross unrealized losses	(899,000)	(1,254,000)
Fair value	387,347,000	334,655,000
US Government Agencies Debt Securities [Member]
Amortized cost	242,522,000	185,103,000
Securities available for sale, gross unrealized gains	516,000	2,449,000
Securities available for sale, gross unrealized losses	(897,000)	(1,142,000)
Fair value	242,141,000	186,410,000
Collateralized Mortgage Backed Securities [Member]
Amortized cost	23,869,000	41,998,000
Securities available for sale, gross unrealized gains	1,021,000	554,000
Securities available for sale, gross unrealized losses	0	(82,000)
Fair value	24,890,000	42,470,000
Municipal General Obligation Bonds [Member]
Amortized cost	101,991,000	98,245,000
Securities available for sale, gross unrealized gains	5,833,000	2,864,000
Securities available for sale, gross unrealized losses	0	(30,000)
Fair value	107,824,000	101,079,000
Municipal Revenue Bonds [Member]
Amortized cost	11,521,000	4,133,000
Securities available for sale, gross unrealized gains	473,000	63,000
Securities available for sale, gross unrealized losses	(2,000)	0
Fair value	11,992,000	4,196,000
Other Debt and Equity Securities [Member]
Amortized cost	500,000	500,000
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	0	0
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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