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Provisions and contingent liabilities - Movement of the provision for social responsibility (Details) - Minera Yanacocha SRL and subsidiary [Member] - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Provisions and contingent liabilities      
Opening balance $ 18,010 $ 21,689 $ 24,335
Additional provisions 888    
Payments (572) (3,679) (2,646)
Ending balance 18,326 18,010 21,689
Classification by maturity [Abstract]      
Current portion 761 8,351  
Non-current portion 17,565 9,659 21,689
Ending balance $ 18,326 $ 18,010 $ 21,689