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Financial - risk management objectives and policies - Additional information (Details)
 12 Months Ended
Dec. 31, 2020
USD ($)
$ / £
Dec. 31, 2019
$ / £
Dec. 31, 2018
$ / £
Disclosure Of Financial risk management [Line Items]      
Decrease in exchange rate basis points 10.00% 10.00% 10.00%
Sociedad Minera Cerro Verde S.A.A. [Member]      
Disclosure Of Financial risk management [Line Items]      
Consolidated minimum net worth | $ $ 2,711,389    
Sociedad Minera Cerro Verde S.A.A. [Member] | Minimum      
Disclosure Of Financial risk management [Line Items]      
10% increase in copper price 3.524 2.865 2.974
10% decrease in copper price 2.884 2.344 2.433
Sociedad Minera Cerro Verde S.A.A. [Member] | Maximum      
Disclosure Of Financial risk management [Line Items]      
10% increase in copper price 3.876 3.085 2.979
10% decrease in copper price 3.172 2.524 2.437