Note 9 - Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) by Component, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Balance	$ 90,870	$ 91,480	$ 87,545	$ 85,858	$ 91,480	$ 85,858
Net current period other comprehensive income (loss)	1,228	(2,080)	497	1,197
Balance	93,233	90,870	88,544	87,545	93,233	88,544
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance	140	2,220	1,089	(108)	2,220	(108)
Other comprehensive income before reclassification	1,231		937		(829)	2,196
Amounts reclassified from accumulated other comprehensive income (loss)	(3)		(440)		(23)	(502)
Net current period other comprehensive income (loss)	1,228		497		(852)	1,694
Balance	1,368	140	1,586	1,089	1,368	1,586
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(5,704)	(5,704)	(5,227)	(5,227)	(5,704)	(5,227)
Other comprehensive income before reclassification	0		0		0	0
Balance	(5,704)	(5,704)	(5,227)	(5,227)	(5,704)	(5,227)
AOCI Attributable to Parent [Member]
Balance	(5,564)	(3,484)	(4,138)	(5,335)	(3,484)	(5,335)
Other comprehensive income before reclassification	1,231		937		(829)	2,196
Amounts reclassified from accumulated other comprehensive income (loss)	(3)		(440)		(23)	(502)
Net current period other comprehensive income (loss)	1,228	(2,080)	497	1,197	(852)	1,694
Balance	$ (4,336)	$ (5,564)	$ (3,641)	$ (4,138)	$ (4,336)	$ (3,641)