Note 9 - Other Comprehensive Income - Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Balance			$ 313,872	$ 286,519
Net current period other comprehensive gain (loss)	$ 79	$ (1,010)	968	3,809
Reclassification adjustment for securities (gains) realized in income (net of tax of $(11), $0, $(11), and $0, respectively)	(20)		(20)
Balance	334,255	311,570	334,255	311,570
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance			(1,211)	965
Net current period other comprehensive gain (loss)			950	4,110
Reclassification adjustment for securities (gains) realized in income (net of tax of $(11), $0, $(11), and $0, respectively)			(20)
Balance	(281)	5,075	(281)	5,075
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Balance			(16)	(60)
Net current period other comprehensive gain (loss)			38	(301)
Reclassification adjustment for securities (gains) realized in income (net of tax of $(11), $0, $(11), and $0, respectively)
Balance	22	(361)	22	(361)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance			(272)	(273)
Net current period other comprehensive gain (loss)
Reclassification adjustment for securities (gains) realized in income (net of tax of $(11), $0, $(11), and $0, respectively)
Balance	(272)	(273)	(272)	(273)
AOCI Attributable to Parent [Member]
Balance			(1,499)	632
Net current period other comprehensive gain (loss)			968	3,809
Reclassification adjustment for securities (gains) realized in income (net of tax of $(11), $0, $(11), and $0, respectively)			(20)
Balance	$ (531)	$ 4,441	$ (531)	$ 4,441