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Leases - Summary of Changes in ROU Assets (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2019
Changes in Right-of-Use Assets [Roll Forward]      
Balance, beginning of period $ 43,361 $ 30,203  
Balance, end of period 33,543 43,361 $ 43,361
Impairment charge 0 40,050  
Cost [member]      
Changes in Right-of-Use Assets [Roll Forward]      
Balance, beginning of period 60,779 34,983  
Additions 5,534 42,415  
Transfer out (10,458) (16,619)  
Balance, end of period 55,855 60,779 60,779
Assets acquired from Tahoe     8,500
Accumulated Depreciation [member]      
Changes in Right-of-Use Assets [Roll Forward]      
Balance, beginning of period (17,418) (4,780)  
Amortization (14,244) (20,103)  
Transfer out 9,350 7,465  
Balance, end of period $ (22,312) (17,418) $ (17,418)
Accumulated Depreciation [member] | Manantial Espejo Mine and COSE and Joaquin Projects [Member]      
Changes in Right-of-Use Assets [Roll Forward]      
Impairment charge   $ 2,400