Note 6 - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
Due in one year or less, Fair value	$ 14,413
Due after one year through five years, Fair value	238,936
Due after five years through ten years, Fair value	40,467
Due after ten years, Fair value	33,509
Total investment securities available-for-sale, Fair value	327,325	$ 349,710
Due in one year or less, Amortized cost	14,202
Due after one year through five years, Amortized cost	233,534
Due after five years through ten years, Amortized cost	39,996
Due after ten years, Amortized cost	33,456
Investment securities available-for-sale, debt securities amortized cost	$ 321,188	$ 349,385

Amortized cost of 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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