Note 2 - Business Segments and Sales of Products (Details Textual) $ in Millions	3 Months Ended
Mar. 31, 2024 USD ($) Segment	Mar. 31, 2023 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of Reportable Segments \| Segment	4
Lucky Friday [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Business interruption insurance proceeds received	$ 17.4
Financially-settled Forward Contracts [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Derivative, Gain (Loss) on Derivative, Net, Total	$ 3.1	$ 0.9

Proceeds from Business Interruption Insurance Policy

No definition available.

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- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4A

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-18

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- 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.

+ References

No definition available.

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