Note 7 - Accrued Retirement Benefits (Details Textual) $ in Thousands	1 Months Ended		12 Months Ended
	Nov. 30, 2022 USD ($)	Aug. 30, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Defined Benefit Plan, Number of People Receiving Pension Benefits	167
Defined Benefit Plan, Plan Assets, Benefits Paid	$ 14,500		$ 1,188	$ 16,907
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax			$ 6,900	8,300
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction Period (Day)			105 days
Defined Benefit Plan, Plan Assets, Contributions by Employer		$ 5,700	$ 128	$ 5,828
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year			$ 0