Note 2 - Investment Securities - Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Securities available for sale, amortized cost, due in one year or less	$ 22,320
Securities available for sale, fair value, due in one year or less	22,167
Securities available for sale, amortized cost, due after one year through five years	58,207
Securities available for sale, fair value, due after one year through five years	56,861
Securities available for sale, amortized cost, due after five years through ten years	30,999
Securities available for sale, fair value, due after five years through ten years	30,505
Securities available for sale, amortized cost, due after ten years	18,644
Securities available for sale, fair value, due after ten years	18,702
Securities available for sale, amortized cost, single maturity	130,170
Securities available for sale, fair value, single maturity	128,235
Securities available for sale, amortized cost, mortgage-backed securities and CMO	128,462
Securities available for sale, fair value, mortgage-backed securities and CMO	123,203
Securities available for sale, amortized cost	258,632	$ 273,878
Securities available for sale, fair value	251,438	$ 271,172
Debt Securities [Member]
Securities available for sale, amortized cost	258,632
Securities available for sale, fair value	$ 251,438

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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