XML 412 R102.htm IDEA: XBRL DOCUMENT v3.22.1
Accounting policies - Summary of Key assumptions used in the Income and Market Approach (Detail)
 12 Months Ended
Dec. 31, 2021
$ / oz
Dec. 31, 2020
$ / oz
Dec. 31, 2021
ZAR-kg
Dec. 31, 2021
$ / oz
Dec. 31, 2020
ZAR-kg
Dec. 31, 2020
$ / oz
Dec. 31, 2019
$ / oz
Dec. 31, 2019
ZAR-kg
Dec. 31, 2019
$ / oz
Disclosure of Detailed Information of Key Assumptions Used in the Income and Market Approach Explanatory [line items]                  
Resource value per ounce 0 76              
Discount rates – real 9.00% 8.40%              
Life-of-mine 6 years 7 years              
Year 1 - 3 | Bottom of range                  
Disclosure of Detailed Information of Key Assumptions Used in the Income and Market Approach Explanatory [line items]                  
Gold price per ounce/kg 1,600 1,600              
Year 1 - 3 | Top of range                  
Disclosure of Detailed Information of Key Assumptions Used in the Income and Market Approach Explanatory [line items]                  
Gold price per ounce/kg 1,750 1,800              
Year 4                  
Disclosure of Detailed Information of Key Assumptions Used in the Income and Market Approach Explanatory [line items]                  
Gold price per ounce/kg 1,550 1,500 780,000 2,070 750,000 2,000 1,350 630,000 1,850