Note 6 - Available-for-Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	$ 327,325	$ 349,710
Investment securities available-for-sale, debt securities gross unrealized holding gains	6,646	1,602
Investment securities available-for-sale, debt securities gross unrealized holding losses	(509)	(1,277)
Investment securities available-for-sale, debt securities amortized cost	321,188	349,385
US Government Agencies Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	31,074	69,298
Investment securities available-for-sale, debt securities gross unrealized holding gains	83	8
Investment securities available-for-sale, debt securities gross unrealized holding losses	(7)	(213)
Investment securities available-for-sale, debt securities amortized cost	30,998	69,503
US States and Political Subdivisions Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	62,838	50,781
Investment securities available-for-sale, debt securities gross unrealized holding gains	935	860
Investment securities available-for-sale, debt securities gross unrealized holding losses	(478)	(19)
Investment securities available-for-sale, debt securities amortized cost	62,381	49,940
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	140,644	134,829
Investment securities available-for-sale, debt securities gross unrealized holding gains	3,257	371
Investment securities available-for-sale, debt securities gross unrealized holding losses		(504)
Investment securities available-for-sale, debt securities amortized cost	137,387	134,962
Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	84,646	86,610
Investment securities available-for-sale, debt securities gross unrealized holding gains	2,315	260
Investment securities available-for-sale, debt securities gross unrealized holding losses	(1)	(535)
Investment securities available-for-sale, debt securities amortized cost	82,332	86,885
Collateralized Debt Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	71	79
Investment securities available-for-sale, debt securities gross unrealized holding losses	(14)	(6)
Investment securities available-for-sale, debt securities amortized cost	85	85
Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	8,052	8,113
Investment securities available-for-sale, debt securities gross unrealized holding gains	56	103
Investment securities available-for-sale, debt securities gross unrealized holding losses	(9)
Investment securities available-for-sale, debt securities amortized cost	$ 8,005	$ 8,010

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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