Note 6 - Accrued Retirement Benefits (Details Textual) $ in Thousands	1 Months Ended				12 Months Ended
	Nov. 30, 2022 USD ($)	Aug. 31, 2022 USD ($)	Nov. 30, 2021 USD ($)	Aug. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 31, 2021 USD ($)
Defined Benefit Plan, Number of People Receiving Pension Benefits	167		384
Defined Benefit Plan, Plan Assets, Benefits Paid	$ 14,500		$ 10,400		$ 16,907	$ 14,550
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax					8,300	15,600
Defined Benefit Plan, Plan Assets, Contributions by Employer		$ 5,700		$ 1,000	5,828	$ 1,682
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year					$ 0		$ 600