Note 6 - Other Comprehensive Income (Loss) - Components of Other Comprehensive Income (Loss) and Related Tax Effects (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Net unrealized gains (losses) arising during the period, before tax	$ (479)	$ 313
Net unrealized gains (losses) arising during the period, tax effect	(133)	125
Net unrealized gains (losses) arising during the period, net of tax	(346)	188
Other comprehensive income (loss), before tax	(479)	313
Other comprehensive income (loss), tax effect	(133)	125
Other comprehensive income (loss), net of tax	$ (346)	$ 188

Amount before tax, after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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