Note 4 - Securities - Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortized cost, due in one year or less, available for sale securities	$ 19,102
Fair value, due in one year or less, available for sale securities	19,196
Amortized cost, due after one year through five years, available for sale securities	6,356
Fair value, due after one year through five years, available for sale securities	6,560
Amortized cost, due after five years through ten years, available for sale securities	150,410
Fair value, due after five years through ten years, available for sale securities	153,322
Amortized cost, due after ten years, available for sale securities	258,176
Fair value, due after ten years, available for sale securities	259,941
Amortized cost, total securities available for sale	434,044	$ 435,166
Fair value, total securities available for sale	$ 439,019	$ 435,263

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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