Note 8 - Reclassifications Out of Other Comprehensive Income - Items Reclassified to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
	$ 434	$ 224	$ 1,199	$ 1,025
Tax expense related to realized gains on securities sold	176	434	518	787
Reclassification out of Accumulated Other Comprehensive Income [Member]
	19	138	28	141
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Realized gains on sales of securities held for sale during the period consider available for sale	29	209	42	214
Tax expense related to realized gains on securities sold	$ 10	$ 71	$ 14	$ 73