Note 5 - Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 3,434	$ 3,231	$ 6,926	$ 7,213
Tax effect	(572)	(845)	(1,129)	(1,967)
Net income	2,862	2,386	5,797	5,246
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Unrealized net holding gains on available-for-sale securities	2	115	3	864
Income before income taxes	2	115	3	864
Tax effect	(1)	(40)	(1)	(294)
Net income	$ 1	$ 75	$ 2	$ 570