Annual report pursuant to Section 13 and 15(d)

Restricted Cash (Details)

v3.10.0.1
Restricted Cash (Details) - USD ($)
Dec. 31, 2018
Dec. 31, 2017
Restricted Cash    
Restricted cash $ 7,458,000 $ 7,558,000
Reclamation bonding requirement 29,880,000  
Certificate of deposit [Member]    
Restricted Cash    
Restricted cash   100,000
Money Market Funds [Member]    
Restricted Cash    
Restricted cash 7,458,000 $ 7,458,000
Money Market Funds [Member] | Surety Bond [Member]    
Restricted Cash    
Restricted cash pledged as collateral $ 7,444,000