Note 8 - Components of Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Balance	$ 183,726	$ 190,238
Balance	191,559	181,228
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance	76	(5,072)
Unrealized holding gain (loss) on available for sale securities, net of tax	3,870	4,553
Reclassification adjustment, net of tax	(16)	(9)
Balance	3,930	(528)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(8,582)	(7,013)
Unrealized holding gain (loss) on available for sale securities, net of tax	0
Reclassification adjustment, net of tax		0
Balance	(8,582)	(7,013)
AOCI Attributable to Parent [Member]
Balance	(8,506)	(12,085)
Unrealized holding gain (loss) on available for sale securities, net of tax	3,870	4,553
Reclassification adjustment, net of tax	(16)	(9)
Balance	$ (4,652)	$ (7,541)