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IMPAIRMENT AND REVERSAL OF NON-CURRENT ASSETS - Assumptions (Details)
 3 Months Ended 6 Months Ended 12 Months Ended
Sep. 30, 2018
USD ($)
Jun. 30, 2018
USD ($)
$ / ounce
Rate
Dec. 31, 2019
USD ($)
$ / ounce
ozt
$ / pound
Rate
Dec. 31, 2018
USD ($)
$ / ounce
$ / pound
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Impairment (reversals) charges     $ (1,423,000,000) $ 900,000,000
Copper | Average        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
WACC       10.00%
Gold[member]        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | $ / ounce     1,300 1,250
LOM year     19 years 15 years
Gold[member] | Average        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
NAV multiple     1,200.000 1,050.000
WACC     4.00% 7.00%
Gold[member] | Minimum        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | ozt     20  
WACC     3.00% 4.00%
Gold[member] | Maximum        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | ozt     30  
WACC     7.00% 11.00%
Silver | Minimum        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | ozt     0.28  
Silver | Maximum        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | ozt     0.42  
Long-term | Copper        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | $ / pound     3.00 2.85
Acacia Mining PLC        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound)   1,200    
WACC | Rate     11.00%  
Acacia Mining PLC | One percent increase in WACC [Member]        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Estimated Change in Discount Rate Used In Current Measurement Of Fair Value Less Costs Of Disposal | Rate   1.00%    
Lagunas Norte | Minimum        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
NAV multiple     1.100  
Lagunas Norte | Maximum        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
NAV multiple     1.200  
$100 Increase in Gold Price | Acacia Mining PLC        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | $ / ounce   100    
Estimated Change in Discount Rate Used In Current Measurement Of Fair Value Less Costs Of Disposal | Rate   1.00%    
$100 Decrease in Gold Price | Acacia Mining PLC        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | $ / ounce   100    
Impairment (reversals) charges   $ 98    
$0.25 decrease in copper        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Mineral price (gold, in dollars per ounce; copper, in dollars per pound) | $ / ounce     0  
Other impaired assets [member] | Lagunas Norte        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Impairment (reversals) charges     $ 166,000,000  
Estimated gold price     1,250  
Impairment (reversals) of long lived assets        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
Impairment (reversals) charges     $ (1,423,000,000) $ 746,000,000
Individual assets or cash-generating units [member] | Lagunas Norte        
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [line items]        
WACC | Rate     3.80%  
Impairment (reversals) charges $ 405,000,000   $ 12,000,000 $ 405,000,000
Estimated gold price     $ 1,200