Note 16 - Accumulated Other Comprehensive Income - Components of Accumulated Other Comprehensive Income, Net of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Balance	$ 428,819	$ 332,857	$ 350,714
Other comprehensive (loss) income, net	(417)	(77)	(589)
Balance	426,730	428,819	332,857
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance	866	(285)	975
Other comprehensive (loss) income before reclassifications	544	1,117	(1,748)
Reclassified from AOCI	(304)	34	488
Other comprehensive (loss) income, net	240	1,151	(1,260)
Balance	1,106	866	(285)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(2,372)	(1,144)	(1,815)
Other comprehensive (loss) income before reclassifications	(961)	(1,448)	446
Reclassified from AOCI	304	220	225
Other comprehensive (loss) income, net	(657)	(1,228)	671
Balance	(3,029)	(2,372)	(1,144)
AOCI Attributable to Parent [Member]
Balance	(1,506)	(1,429)	(840)
Other comprehensive (loss) income before reclassifications	(417)	(331)	(1,302)
Reclassified from AOCI	0	254	713
Other comprehensive (loss) income, net	(417)	(77)	(589)
Balance	$ (1,923)	$ (1,506)	$ (1,429)