v3.26.1
ASSET RETIREMENT AND ENVIRONMENTAL OBLIGATIONS (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Unusual Risk or Uncertainty [Line Items]    
Asset retirement obligations, noncurrent $ 8.0 $ 7.7
Estimated undiscounted cash flows, to satisfy obligation $ 51.3 51.4
Remediation term 30 years  
Discount rate 4.84%  
Environmental obligations, undiscounted cost $ 39.9 40.3
Accrued environmental loss contingencies, noncurrent 18.4 18.4
Closure and reclamation obligations, financial assurances $ 46.2 $ 46.2
Minimum    
Unusual Risk or Uncertainty [Line Items]    
Asset retirement obligations, credit-adjusted risk free rate 6.50%  
Maximum    
Unusual Risk or Uncertainty [Line Items]    
Asset retirement obligations, credit-adjusted risk free rate 8.80%