Note 2 - Business Segments and Sales of Products (Details Textual) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2026 USD ($) Segment	Sep. 30, 2025 USD ($)
Segment Reporting [Line Items]
Derivative, Gain (Loss) on Derivative, Net, Total	$ (13.2)	$ (8.5)	$ (13.5)	$ (9.8)
Derivative, Gain (loss) on Derivative	(13.2)	(8.5)	$ (13.5)	(9.8)
Number of Reportable Segments \| Segment			3
Keno Hill [Member]
Segment Reporting [Line Items]
Revenues	$ 5.9	$ 1.9	$ 9.7	$ 4.1

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details