Note 2 - Business Segments and Sales of Products (Details Textual) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) Segment	Jun. 30, 2024 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Derivative, Gain (Loss) on Derivative, Net, Total	$ 3.8	$ 12.5	$ 1.3	$ 9.4
Number of Reportable Segments | Segment			4
Lucky Friday [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Business interruption insurance proceeds received		17.8		35.2
Keno Hill [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 1.2	$ 1.1	$ 2.2	$ 1.5