Quarterly report pursuant to Section 13 or 15(d)

Asset Retirement Obligations (Details)

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Asset Retirement Obligations (Details) - USD ($)
$ in Thousands
6 Months Ended 12 Months Ended
Jun. 30, 2020
Dec. 31, 2019
Estimated Future Cash Undiscounted Amount $ 29,800  
Estimated future cost to complete reclamation including inflation $ 39,900  
Change in estimated liability   $ 11
Minimum    
Discount Rate Of Asset Retirement Obligations 0.33%  
Maximum    
Discount Rate Of Asset Retirement Obligations 7.25%