Annual report pursuant to Section 13 and 15(d)

Restricted Cash (Details)

v3.19.3.a.u2
Restricted Cash (Details) - USD ($)
$ in Thousands
Dec. 31, 2019
Dec. 31, 2018
Restricted Cash    
Restricted cash $ 7,463 $ 7,458
Surety Bond [Member]    
Restricted Cash    
Reclamation bonding requirement 29,864  
Money Market Funds [Member] | Surety Bond [Member]    
Restricted Cash    
Restricted cash pledged as collateral $ 7,444