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REVENUE - Narrative (Details)
Dec. 31, 2019
$ / ounce
$ / pound
Dec. 31, 2018
$ / pound
Disclosure of Disaggregation of Revenue [Line Items]    
Percent change in commodity prices used for sensitivity analysis 10.00%  
Gold[member]    
Disclosure of Disaggregation of Revenue [Line Items]    
Percentage of composition of principal product (as percent) 90.00%  
Average price of sales subject to final settlement (copper in dollars per pound; gold in dollars per oz) | $ / ounce 1,524  
Copper    
Disclosure of Disaggregation of Revenue [Line Items]    
Average price of sales subject to final settlement (copper in dollars per pound; gold in dollars per oz) | $ / pound 2.80 2.71