Note 6 - Debt Securities Available-for-sale (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	$ 344,367	$ 344,221
Investment securities available-for-sale, debt securities gross unrealized holding gains	825	394
Investment securities available-for-sale, debt securities gross unrealized holding losses	(5,423)	(9,422)
Investment securities available-for-sale, debt securities amortized cost	348,965	353,249
US Government Agencies Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	69,359	68,409
Investment securities available-for-sale, debt securities gross unrealized holding losses	(1,123)	(2,072)
Investment securities available-for-sale, debt securities amortized cost	70,482	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	53,331	66,313
Investment securities available-for-sale, debt securities gross unrealized holding gains	367	195
Investment securities available-for-sale, debt securities gross unrealized holding losses	(61)	(464)
Investment securities available-for-sale, debt securities amortized cost	53,025	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	133,039	125,913
Investment securities available-for-sale, debt securities gross unrealized holding gains	192	79
Investment securities available-for-sale, debt securities gross unrealized holding losses	(2,411)	(4,251)
Investment securities available-for-sale, debt securities amortized cost	135,258	130,085
Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	80,467	75,491
Investment securities available-for-sale, debt securities gross unrealized holding gains	188	87
Investment securities available-for-sale, debt securities gross unrealized holding losses	(1,777)	(2,549)
Investment securities available-for-sale, debt securities amortized cost	82,056	77,953
Collateralized Debt Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	112	116
Investment securities available-for-sale, debt securities gross unrealized holding losses	(10)	(6)
Investment securities available-for-sale, debt securities amortized cost	122	122
Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale, debt securities	8,059	7,979
Investment securities available-for-sale, debt securities gross unrealized holding gains	78	33
Investment securities available-for-sale, debt securities gross unrealized holding losses	(41)	(80)
Investment securities available-for-sale, debt securities amortized cost	$ 8,022	$ 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).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
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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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