Note 2 - Business Segments and Sales of Products (Details Textual) $ in Millions	3 Months Ended
Mar. 31, 2025 USD ($) Segment	Mar. 31, 2024 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Derivative, Gain (Loss) on Derivative, Net, Total	$ 5.1	$ 3.1
Number of Reportable Segments \| Segment	4
Lucky Friday [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Business interruption insurance proceeds received		17.4
Keno Hill [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 1.0	$ 0.3

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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+ Details