Note 3 - Components of Pension and Other Post-employment Benefit (OPEB) Plans Net Periodic Benefit Costs: (Details Textual) - USD ($) $ in Thousands		9 Months Ended
	Jun. 30, 2021	Sep. 30, 2021
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		$ (22)
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax	$ 766
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect, Total	$ 265
Commodity Contract [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		$ 22