Quarterly report pursuant to Section 13 or 15(d)

Asset Retirement Obligations (Details)

v3.20.2
Asset Retirement Obligations (Details) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Asset Retirement Obligations    
Beginning of period $ 30,972  
Change in estimated reclamation costs (170)  
Accretion expense 433 $ 431
End of period $ 31,235