Note 4 - Environmental and Reclamation Activities - Schedule of Reclamation and Closure Costs Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Environmental and Reclamation Activities [Abstract]
Beginning balance	$ 113,231	$ 116,048	$ 108,374
Accruals for estimated costs	2,874	4,952
Accretion expense	5,995	6,454	5,912
Revision of estimated cash flows due to changes in reclamation plans	452	(8,781)	2,543
Payment of reclamation obligations	(5,553)	(5,442)	(781)
Ending balance	$ 116,999	$ 113,231	$ 116,048