Note 16 - Components of Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance	$ 184,896	$ 178,263	$ 172,114
Less amortization of prior service cost included in net periodic pension cost, net of tax	(86)	(71)	(72)
Reclassification of stranded tax effects from change in tax rate
Transfer from held-to-maturity to available-for-sale securities, net of tax of $237	891
Balance	190,238	184,896	178,263
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	(3,704)	(3,588)	(2,667)
Unrealized holding gain (loss) on available for sale securities, net of tax	(2,246)	546	(800)
Reclassification adjustment, net of tax	(13)	(6)	(121)
Net pension gain (loss) arising during the period, net of tax
Less amortization of prior service cost included in net periodic pension cost, net of tax
Reclassification of stranded tax effects from change in tax rate		(656)
Transfer from held-to-maturity to available-for-sale securities, net of tax of $237	891
Balance	(5,072)	(3,704)	(3,588)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(5,991)	(5,071)	(5,270)
Unrealized holding gain (loss) on available for sale securities, net of tax		0	0
Reclassification adjustment, net of tax			0
Net pension gain (loss) arising during the period, net of tax	(936)	213	271
Less amortization of prior service cost included in net periodic pension cost, net of tax	(86)	(71)	(72)
Reclassification of stranded tax effects from change in tax rate		(1,062)
Transfer from held-to-maturity to available-for-sale securities, net of tax of $237
Balance	(7,013)	(5,991)	(5,071)
AOCI Attributable to Parent [Member]
Balance	(9,695)	(8,659)	(7,937)
Unrealized holding gain (loss) on available for sale securities, net of tax	(2,246)	546	(800)
Reclassification adjustment, net of tax	(13)	(6)	(121)
Net pension gain (loss) arising during the period, net of tax	(936)	213	271
Less amortization of prior service cost included in net periodic pension cost, net of tax	(86)	(71)	(72)
Reclassification of stranded tax effects from change in tax rate		(1,718)
Transfer from held-to-maturity to available-for-sale securities, net of tax of $237	891
Balance	$ (12,085)	$ (9,695)	$ (8,659)