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PROVISIONS (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Provisions    
Provisions at beginning of period $ 937.9  
Additions 42.2  
Reductions (90.6)  
Reclamation spending (20.6)  
Accretion 25.5  
Reclamation expense 23.5  
Disposals (111.2)  
Provisions at end of period 806.7 $ 937.9
Current portion 50.8  
Non-current portion 755.9  
Other operating expense 113.8 266.4
Reclamation and remediation obligations    
Provisions    
Provisions at beginning of period 867.0  
Additions 31.8  
Reductions (38.2)  
Reclamation spending (20.6)  
Accretion 25.5  
Reclamation expense 23.5  
Disposals (110.0)  
Provisions at end of period 779.0 867.0
Current portion 50.4  
Non-current portion 728.6  
Other operating expense 23.5 1.8
Letter of credit issued to various agencies 463.2 384.7
Surety bonds outstanding $ 317.0 $ 307.4
Reclamation and remediation obligations | Minimum    
Provisions    
Discount rate used in estimating site restoration cost obligation (in percent) 3.90% 1.30%
Inflation rate used in estimating the site restoration cost obligation (in percent) 2.00% 2.30%
Reclamation and remediation obligations | Maximum    
Provisions    
Discount rate used in estimating site restoration cost obligation (in percent) 8.80% 10.30%
Inflation rate used in estimating the site restoration cost obligation (in percent) 8.70% 5.30%
Other    
Provisions    
Provisions at beginning of period $ 70.9  
Additions 10.4  
Reductions (52.4)  
Disposals (1.2)  
Provisions at end of period 27.7 $ 70.9
Current portion 0.4  
Non-current portion $ 27.3