Note 8 - Components of Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Balance	$ 190,238	$ 184,896
Balance	181,228	185,537
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance	(5,072)	(3,704)
Unrealized holding gain (loss) on available for sale securities, net of tax	4,553	(2,655)
Reclassification adjustment, net of tax	(9)
Balance	(528)	(6,359)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(7,013)	(5,991)
Unrealized holding gain (loss) on available for sale securities, net of tax	0	0
Reclassification adjustment, net of tax	0
Balance	(7,013)	(5,991)
AOCI Attributable to Parent [Member]
Balance	(12,085)	(9,695)
Unrealized holding gain (loss) on available for sale securities, net of tax	4,553	(2,655)
Reclassification adjustment, net of tax	(9)
Balance	$ (7,541)	$ (12,350)