Note 4 - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Due in one year or less, Fair value	$ 10,740
Due after one year through five years, Fair value	243,551
Due after five years through ten years, Fair value	73,046
Due after ten years, Fair value	22,373
Total investment securities available-for-sale, Fair value	349,710	$ 344,221
Due in one year or less, Amortized cost	10,743
Due after one year through five years, Amortized cost	243,968
Due after five years through ten years, Amortized cost	72,787
Due after ten years, Amortized cost	21,887
Investment securities available-for-sale, debt securities amortized cost	$ 349,385	$ 353,249

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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