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Accounting Policies - Summary of Significant Assumptions Used in the Group's Impairment Assessments (FVLCOD calculations) (Detail)
 12 Months Ended
Dec. 31, 2020
Exchange_Rates
T
Dec. 31, 2019
Exchange_Rates
T
Dec. 31, 2018
Exchange_Rates
$ / per_oz
$ / per_oz
ZAR-kg
T
Dec. 31, 2020
$ / per_oz
Dec. 31, 2020
$ / per_oz
Dec. 31, 2020
ZAR-kg
Dec. 31, 2020
$ / oz
Dec. 31, 2019
$ / per_oz
Dec. 31, 2019
$ / per_oz
Dec. 31, 2019
ZAR-kg
Dec. 31, 2019
$ / oz
Disclosure of changes in accounting estimates [line items]                      
Resource value per ounce         76       70    
Nominal discount rate 8.40% 8.50%                  
Life of mine 7 years 10 years                  
South deep [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 86 years 75 years 75 years                
Tarkwa [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 14 years 14 years 14 years                
Damang [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 5 years 6 years 7 years                
Cerro Cerona [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 10 years 13 years 12 years                
St Ives [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 8 years 9 years 7 years                
Agnew [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 5 years 4 years 4 years                
Granny Smith [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 10 years 13 years 12 years                
Gruyere [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 9 years 11 years 12 years                
Salares Norte [member]                      
Disclosure of changes in accounting estimates [line items]                      
Life of mine 12 years                    
Rand [member]                      
Disclosure of changes in accounting estimates [line items]                      
Resource value per ounce     17   6       16    
Nominal discount rate 14.50% 14.10% 13.50%                
Inflation rate 4.70% 5.30% 5.50%                
Australia, Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Resource value per ounce     28   88       77    
Real discount rates 3.50% 3.50% 3.40%                
Ghanaian cedi [member]                      
Disclosure of changes in accounting estimates [line items]                      
Resource value per ounce     44   76       70    
Real discount rates 8.40% 8.50% 9.50%                
Peru, Nuevos Soles [member]                      
Disclosure of changes in accounting estimates [line items]                      
Resource value per ounce     70   34       34    
Real discount rates 4.50% 5.00% 4.90%                
Chile, Pesos [member]                      
Disclosure of changes in accounting estimates [line items]                      
Resource value per ounce         4            
Real discount rates 6.00%                    
Year 1 [member] | US Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price     1,200   1,600       1,500    
Copper price per tonne | T 5,797 5,730 5,951                
Year 1 [member] | Rand [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price | ZAR-kg     525,000     900,000       700,000  
Long-term exchange rates | Exchange_Rates 17.50 14.50 13.61                
Year 1 [member] | Australia, Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price     1,600 2,190       2,150      
Long-term exchange rates | Exchange_Rates 0.76 0.70 0.75                
Year 2 [member] | US Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price     1,300   1,700       1,400    
Copper price per tonne | T 6,612 6,612 6,612                
Year 2 [member] | Rand [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price | ZAR-kg     550,000     850,000       650,000  
Long-term exchange rates | Exchange_Rates 15.55 14.50 13.16                
Year 2 [member] | Australia, Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price     1,700 2,300       1,970      
Long-term exchange rates | Exchange_Rates 0.74 0.71 0.76                
Year 3 [member] | US Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price     1,300   1,600       1,400    
Year 3 [member] | Rand [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price | ZAR-kg     550,000     800,000       650,000  
Year 3 [member] | Australia, Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price     1,700 2,200       1,970      
Long-term exchange rates | Exchange_Rates 0.73 0.71 0.76                
Year 4 [member] | US Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price     1,300   1,500   1,500   1,350   1,350
Year 4 [member] | Rand [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price | ZAR-kg     550,000     750,000       630,000  
Year 4 [member] | Australia, Dollars [member]                      
Disclosure of changes in accounting estimates [line items]                      
Gold price     1,700 2,000       1,850      
Long-term exchange rates | Exchange_Rates 0.75 0.73 0.76