Note 5 - Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 3,982	$ 3,053
Tax effect	(1,122)	(788)
Net income	2,860	2,265
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	749	389
Other-than-temporary impairment losses on investment securities		(70)
Income before income taxes	749	319
Tax effect	(254)	(108)
Net income	$ 495	$ 211