Note 4 - Securities - Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Amortized cost, due in one year or less, available for sale securities	$ 81,642
Fair value, due in one year or less, available for sale securities	81,455
Amortized cost, due after one year through five years, available for sale securities	184,604
Fair value, due after one year through five years, available for sale securities	179,518
Amortized cost, due after five years through ten years, available for sale securities	97,187
Fair value, due after five years through ten years, available for sale securities	94,744
Amortized cost, due after ten years, available for sale securities	95,172
Fair value, due after ten years, available for sale securities	92,768
Amortized cost, total securities available for sale	458,605	$ 336,075
Fair value, total securities available for sale	$ 448,485	$ 331,387

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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