Note 3 -Business Segments, Sales of Products and Significant Customers (Additional Information) (Details) oz in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) Segment oz	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | Segment	5
Derivative, loss on derivative | $	$ 5,800,000	$ 500,000	$ 16,400,000
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent	Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent
Trade | $	45,146,000	$ 36,437,000
Allowance for doubtful accounts | $	$ 0	$ 0
Silver Contracts [Member]
Segment Reporting Information [Line Items]
Metals contained in concentrates (Ounce) | oz	3.1
Gold [Member]
Segment Reporting Information [Line Items]
Metals contained in concentrates (Ounce) | oz	7,580.0
Zinc [Member]
Segment Reporting Information [Line Items]
Metals contained in concentrates (Ounce) | oz	18.6
Lead [Member]
Segment Reporting Information [Line Items]
Metals contained in concentrates (Ounce) | oz	12.0
Environmental Services [Member]
Segment Reporting Information [Line Items]
Revenues | $	$ 474,000