Note 18 - Parent Company Financial Information (Details) - Condensed Statement of Comprehensive Income - 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
Note 18 - Parent Company Financial Information (Details) - Condensed Statement of Comprehensive Income [Line Items]
Net income	$ 3,482	$ 3,494	$ 3,231	$ 3,982	$ 3,012	$ 3,113	$ 2,800	$ 3,053	$ 14,189	$ 11,978	$ 10,803
Net unrealized holding (losses) gains on securities:
Unrealized holding (losses) gains arising during the period, Before tax amount									1,002	(4,192)	(1,419)
Reclassification adjustment for gains included in net income, Before tax amount									(1,500)	(674)	(783)
Other comprehensive loss, Before tax amount									(498)	(4,866)	(2,202)
Unrealized holding (losses) gains arising during the period, Tax expense (benefit)									341	(1,426)	(483)
Reclassification adjustment for gains included in net income, Tax expense (benefit)									(510)	(229)	(266)
Other comprehensive loss, Tax expense (benefit)									(169)	(1,655)	(749)
Unrealized holding (losses) gains arising during the period, Net of tax amount									661	(2,766)	(936)
Reclassification adjustment for gains included in net income, Net of tax amount									(990)	(445)	(517)
Other comprehensive loss, Net of tax amount									(329)	(3,211)	(1,453)
Total comprehensive income, Before tax amount									13,691	7,112	8,601
Total comprehensive income, Tax expense (benefit)									5,731	1,399	1,821
Net income	$ 489	$ 2,554	$ 2,386	$ 2,860	$ 2,269	$ 2,292	$ 2,098	$ 2,265	8,289	8,924	8,233
Total comprehensive income, Net of tax amount									7,960	5,713	6,780
Parent Company [Member]
Note 18 - Parent Company Financial Information (Details) - Condensed Statement of Comprehensive Income [Line Items]
Net income									14,189	11,978	10,803
Net unrealized holding (losses) gains on securities:
Unrealized holding (losses) gains arising during the period, Before tax amount									1,002	(4,192)	(1,419)
Reclassification adjustment for gains included in net income, Before tax amount									(1,500)	(674)	(783)
Other comprehensive loss, Before tax amount									(498)	(4,866)	(2,202)
Unrealized holding (losses) gains arising during the period, Tax expense (benefit)									341	(1,426)	(483)
Reclassification adjustment for gains included in net income, Tax expense (benefit)									(510)	(229)	(266)
Other comprehensive loss, Tax expense (benefit)									(169)	(1,655)	(749)
Unrealized holding (losses) gains arising during the period, Net of tax amount									661	(2,766)	(936)
Reclassification adjustment for gains included in net income, Net of tax amount									(990)	(445)	(517)
Other comprehensive loss, Net of tax amount									(329)	(3,211)	(1,453)
Total comprehensive income, Before tax amount									13,691	7,112	8,601
Tax expense (benefit)									5,900	3,054	2,570
Total comprehensive income, Tax expense (benefit)									5,731	1,399	1,821
Net income									8,289	8,924	8,233
Total comprehensive income, Net of tax amount									$ 7,960	$ 5,713	$ 6,780