Note 8 - Components of Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Balance	$ 184,896	$ 178,263
Unrealized holding gain on securities transferred from held to maturity to available for sale, net of tax of $237	891
Balance	188,157	187,661
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	(3,704)	(3,588)
Unrealized holding gain (loss) on available for sale securities, net of tax	(5,182)	2,294
Reclassification adjustment, net of tax of ($1)		(3)
Unrealized holding gain on securities transferred from held to maturity to available for sale, net of tax of $237	891
Balance	(7,995)	(1,297)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(5,991)	(5,071)
Unrealized holding gain (loss) on available for sale securities, net of tax	0	0
Reclassification adjustment, net of tax of ($1)		0
Unrealized holding gain on securities transferred from held to maturity to available for sale, net of tax of $237	0
Balance	(5,991)	(5,071)
AOCI Attributable to Parent [Member]
Balance	(9,695)	(8,659)
Unrealized holding gain (loss) on available for sale securities, net of tax	(5,182)	2,294
Reclassification adjustment, net of tax of ($1)		(3)
Unrealized holding gain on securities transferred from held to maturity to available for sale, net of tax of $237	891
Balance	$ (13,986)	$ (6,368)