Note 4 - Components of Pension and Other Post-employment Benefit (OPEB) Plans Net Periodic Benefit Costs - Components of Net Periodic Benefit (Credit) Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension Plan [Member]
Service Cost	$ 302	$ 279
Interest Cost	4,135	3,550
Expected Return on Plan Assets	(9,319)	(10,542)
Amortization of Prior Service Credits	0	0
Amortization of Actuarial Loss	758	1,367
Net Periodic Benefit (Credit) Cost	(4,124)	(5,346)
Other Postretirement Benefits Plan [Member]
Service Cost	0	0
Interest Cost	1,974	1,818
Expected Return on Plan Assets	0	0
Amortization of Prior Service Credits	(601)	(601)
Amortization of Actuarial Loss	879	1,629
Net Periodic Benefit (Credit) Cost	$ 2,252	$ 2,846