ASSET RETIREMENT AND ENVIRONMENTAL RECLAMATION OBLIGATIONS - Narrative (Details) $ in Millions	6 Months Ended
Jun. 30, 2024 USD ($) pit
Asset Retirement Obligation And Accrual For Environmental Loss Contingencies [Line Items]
Environmental Loss Contingency, Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag	environmental remediation liability
Colowyo Mine Pit - Final Reclamation
Asset Retirement Obligation And Accrual For Environmental Loss Contingencies [Line Items]
Number of mine pits in final reclamation \| pit	2
New Horizon Mine
Asset Retirement Obligation And Accrual For Environmental Loss Contingencies [Line Items]
Environmental reclamation obligations	$ 67.3
Discounted basis of environmental reclamation obligation	$ 36.8
Discount rate of environmental reclamation obligations (as a percent)	3.25%
Undiscounted future cash outflows of environmental reclamation obligations	$ 57.9

Accrual For Environmental Loss Contingencies, Net Of Discount

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- Definition

Asset Retirement Obligation And Accrual For Environmental Loss Contingencies

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- Definition

Environmental Loss Contingency, Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag

+ References

No definition available.

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- Definition

The number of mine pits in final reclamation.

+ References

No definition available.

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- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

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- Definition

Rate applied to the undiscounted amount of environmental loss contingencies to arrive at the present value recorded as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Undiscounted amount of the accrual for environmental loss contingencies.

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