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PROPERTY, PLANT AND EQUIPMENT - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Sep. 23, 2020
Disclosure of detailed information about property, plant and equipment [line items]      
Quoted borrowing costs capitalised $ 40.5 $ 24.0  
Borrowing costs capitalized, weighted average interest rate 5.80% 6.42%  
5.75% senior notes | Fixed interest rate      
Disclosure of detailed information about property, plant and equipment [line items]      
Interest rate 5.75% 5.75% 5.75%
Mining properties      
Disclosure of detailed information about property, plant and equipment [line items]      
Mining properties, stripping costs capitalized $ 276.3 $ 230.8  
Mining properties, stripping costs capitalized during period 127.3 86.0  
Mining properties, stripping costs, depreciation expense $ 81.8 $ 66.5