Note 11 - Stockholders' Equity - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Balance at December 31	$ 701,769	$ 823,272	$ 1,016,410
Unrealized loss on note receivable	(496)	0	0
Balance at December 31	865,990	701,769	823,272
AOCI Attributable to Parent [Member]
Balance at December 31	2,668	(804)	(236)
Unrealized loss on note receivable	(496)	0	0
Balance at December 31	8,576	2,668	(804)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Before reclassifications	$ 6,404	$ 3,472	$ (568)