Note 10 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Increase (Decrease) in Obligation, Pension Benefits	$ 7,000	$ (20,000)	$ (16,000)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	23,000	(0)	(0)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	5,000	(5,000)	(4,000)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax, Total	6,000	15,000	12,000
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, Total		5,000	(4,000)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	17,000
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	(6,000)
Income Taxes Paid, Net	50,000	180,000	149,000
Unrecognized Tax Benefits	14,000	15,000	$ 15,000	$ 14,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	0	$ 0
Proceeds from Income Tax Refunds				$ 21,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	$ 299,000