Note 6 - Accrued Retirement Benefits - Changes in Benefit Obligations and Plan Assets (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Nov. 30, 2021	Aug. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Change in benefit obligations:
Benefit obligations			$ 54,655	$ 54,128
Interest cost			1,237	1,633
Actuarial (gain) loss			(1,160)	3,588
Benefits paid			(14,550)	(4,694)
Benefit obligations			40,182	54,655
Change in plan assets:
Fair value of plan assets			43,587	44,284
Actual return on plan assets			1,384	3,869
Employer contributions		$ 1,000	1,682	128
Benefits paid	$ (10,400)		(14,550)	(4,694)
Fair value			32,103	43,587
Funded status			(8,079)	(11,068)
Accumulated benefit obligations			$ 40,182	$ 54,655
Discount rate			0.00%	0.00%
Expected long-term return on plan assets			4.00%	4.50%
Minimum [Member]
Change in plan assets:
Discount rate			2.69%	2.28%
Maximum [Member]
Change in plan assets:
Discount rate			2.74%	2.35%