Note 8 - Reclassifications Out of Other Comprehensive Income - Items Reclassified to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Tax expense related to realized gains on securities sold	$ 413	$ 416	$ 930	$ 1,203
	917	903	2,116	1,928
Reclassification out of Accumulated Other Comprehensive Income [Member]
	12	28	40	170
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	18	43	60	257
Tax expense related to realized gains on securities sold	$ 6	$ 15	$ 20	$ 87