Note 7 - Components of Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Balances at December 31, 2020	$ 191,751	$ 200,607
Balances at March 31, 2021	161,289	189,069
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member]
Balances at December 31, 2020	2,854	13,167
Unrealized holding gain (loss) on available for sale securities, net of tax	(33,826)	(12,309)
Reclassification adjustment, net of tax		(4)
Balances at March 31, 2021	(30,972)	854
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balances at December 31, 2020	(6,912)	(10,147)
Unrealized holding gain (loss) on available for sale securities, net of tax	0	0
Reclassification adjustment, net of tax		0
Balances at March 31, 2021	(6,912)	(10,147)
AOCI Attributable to Parent [Member]
Balances at December 31, 2020	(4,058)	3,020
Unrealized holding gain (loss) on available for sale securities, net of tax	(33,826)	(12,309)
Reclassification adjustment, net of tax		(4)
Balances at March 31, 2021	$ (37,884)	$ (9,293)