Note 16 - Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes		$ 3,482	$ 3,494	$ 3,231	$ 3,982	$ 3,012	$ 3,113	$ 2,800	$ 3,053	$ 14,189	$ 11,978	$ 10,803
Tax effect		(2,993)	(940)	(845)	(1,122)	(743)	(821)	(702)	(788)	(5,900)	(3,054)	(2,570)
Net income		$ 489	$ 2,554	$ 2,386	$ 2,860	$ 2,269	$ 2,292	$ 2,098	$ 2,265	8,289	8,924	8,233
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										1,580	866	838
Other-than-temporary impairment losses on investment securities										(80)	(192)	(55)
Income before income taxes										1,500	674	783
Tax effect	[1]									(510)	(229)	(266)
Net income										$ 990	$ 445	$ 517

[1] At rate of 34% for 2017, 2016 and 2015