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Mine Care and Maintenance (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Disclosure of detailed information about property, plant and equipment [line items]    
Mine care and maintenance $ 102,105 $ 23,662
Mine care and maintenance 102,105 23,662
Gross carrying amount [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Mine care and maintenance 84,130 23,662
Mine care and maintenance 84,130 23,662
Gross carrying amount [member] | COVID-19, Suspension of Mines [Member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Mine care and maintenance 58,300  
Mine care and maintenance 58,300  
Accumulated Depreciation [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Mine care and maintenance 17,975 0
Mine care and maintenance 17,975 $ 0
Accumulated Depreciation [member] | COVID-19, Suspension of Mines [Member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Mine care and maintenance 16,800  
Mine care and maintenance $ 16,800