Note 15 - Properties, Plants, Equipment and Mine Development, net, and Lease Commitments (Details textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Capital additions (excluding non-cash items)	$ 214.5
Finance Lease, Right-of-Use Asset, before Accumulated Amortization	108.5	$ 106.9
Finance Lease, Right-of-Use Asset, Accumulated Amortization	94.4	86.5
Lucky Friday [Member]
Capital additions (excluding non-cash items)	49.6
Greens Creek [Member]
Capital additions (excluding non-cash items)	47.8
Mining Assets, Value Beyond Proven and Probable Reserves (VBPP)	83.3	86.3
Casa Berardi [Member]
Capital additions (excluding non-cash items)	60.7
Mining Assets, Value Beyond Proven and Probable Reserves (VBPP)	323.6	323.6
Nevada Operations [Member]
Mining Assets, Value Beyond Proven and Probable Reserves (VBPP)	388.2	383.6
Keno Hill [Member]
Capital additions (excluding non-cash items)	54.9
Mining Assets, Value Beyond Proven and Probable Reserves (VBPP)	$ 95.7	$ 102.1

The economic value of the estimated cash flows of a mining asset beyond that asset's proven and probable reserves.

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Amount of accumulated amortization of right-of-use asset from finance lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
-Section 45
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Amount, before accumulated amortization, of right-of-use asset from finance lease.

+ References

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- Definition

The cash outflow for purchases of and capital improvements on property, plant and equipment (capital expenditures), software, and other intangible assets.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 805
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