Note 11 - Stockholders' Equity - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Balance at December 31	$ 1,037,697	$ 865,990	$ 701,769
Unrealized gain (loss) on note receivable	283	213	(496)
Balance at December 31	1,111,185	1,037,697	865,990
AOCI Attributable to Parent [Member]
Balance at December 31	5,266	8,576	2,668
Unrealized gain (loss) on note receivable	283	213	(496)
Balance at December 31	6,060	5,266	8,576
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Before reclassifications	$ 511	$ (3,523)	$ 6,404