Note 2 - Business Segments and Sales of Products (Details Textual) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($) Segment	Jun. 30, 2025 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Derivative, Gain (Loss) on Derivative, Net, Total	$ 9.9	$ 3.3	$ (0.3)	$ (2.0)
Derivative, Gain (loss) on Derivative	9.9	3.3	$ (0.3)	(2.0)
Number of Reportable Segments | Segment			3
Keno Hill [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 2.2	$ 1.2	$ 3.9	$ 2.2