Note 2 - Business Segments and Sales of Products - Sales of Products (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	$ 189,528	$ 199,500
Less: Smelter and refining charges	(13,014)	(15,973)
Silver Contracts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	86,233	81,532
Gold [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	67,415	75,087
Lead [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	19,483	25,402
Zinc [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	24,964	32,943
Total Metal [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	185,081	198,991
Environmental Remediation Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	$ 4,447	$ 509