Note 2 - Business Segments and Sales of Products - Sales of Products (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	$ 245,657	$ 178,131	$ 435,185	$ 377,631
Less: Smelter and refining charges	(9,282)	(12,220)	(22,296)	(28,193)
Silver Contracts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	112,692	79,489	198,925	161,022
Gold [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	82,469	62,924	149,884	138,010
Lead [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	23,928	21,657	43,411	47,059
Zinc [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	32,496	25,903	57,460	58,846
Total Metal [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	242,303	177,753	427,384	376,744
Environmental Remediation Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total sales	$ 3,354	$ 378	$ 7,801	$ 887