Note 6 - Available-For-Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	$ 361,157	$ 344,221
Investment securities available-for-sale, debt securities gross unrealized holding gains	2,056	394
Investment securities available-for-sale, debt securities gross unrealized holding losses	(1,371)	(9,422)
Investment securities available-for-sale, debt securities amortized cost	360,472	353,249
US Treasury Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	5,281
Investment securities available-for-sale, debt securities amortized cost	5,281
US Government Agencies Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	68,349	68,409
Investment securities available-for-sale, debt securities gross unrealized holding gains	11
Investment securities available-for-sale, debt securities gross unrealized holding losses	(166)	(2,072)
Investment securities available-for-sale, debt securities amortized cost	68,504	70,481
US States and Political Subdivisions Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	51,104	66,313
Investment securities available-for-sale, debt securities gross unrealized holding gains	952	195
Investment securities available-for-sale, debt securities gross unrealized holding losses	(16)	(464)
Investment securities available-for-sale, debt securities amortized cost	50,168	66,582
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	140,553	125,913
Investment securities available-for-sale, debt securities gross unrealized holding gains	519	79
Investment securities available-for-sale, debt securities gross unrealized holding losses	(727)	(4,251)
Investment securities available-for-sale, debt securities amortized cost	140,761	130,085
Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	87,652	75,491
Investment securities available-for-sale, debt securities gross unrealized holding gains	446	87
Investment securities available-for-sale, debt securities gross unrealized holding losses	(452)	(2,549)
Investment securities available-for-sale, debt securities amortized cost	87,658	77,953
Collateralized Debt Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	78	116
Investment securities available-for-sale, debt securities gross unrealized holding losses	(8)	(6)
Investment securities available-for-sale, debt securities amortized cost	86	122
Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	8,140	7,979
Investment securities available-for-sale, debt securities gross unrealized holding gains	128	33
Investment securities available-for-sale, debt securities gross unrealized holding losses	(2)	(80)
Investment securities available-for-sale, debt securities amortized cost	$ 8,014	$ 8,026

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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