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Use of Estimates, Assumptions and Judgements (Narrative) (Details)
 12 Months Ended
Dec. 31, 2020
$ / oz
$ / T
USD ($)
Gold Commodity Type [member]  
Disclosure Of Detailed Information About Use Of Judgements And Estimates Explanatory [line items]  
Long term prices used for reserves and resource estimates related to commodity | $ 1,600
Silver Commodity Type [member]  
Disclosure Of Detailed Information About Use Of Judgements And Estimates Explanatory [line items]  
Long term prices used for reserves and resource estimates related to commodity | $ / oz 21
Lead Commodity [member]  
Disclosure Of Detailed Information About Use Of Judgements And Estimates Explanatory [line items]  
Long term prices used for reserves and resource estimates related to commodity 2,000
Zinc Commodity [member]  
Disclosure Of Detailed Information About Use Of Judgements And Estimates Explanatory [line items]  
Long term prices used for reserves and resource estimates related to commodity 2,270