Annual report pursuant to Section 13 and 15(d)

Mineral Properties - Rollforward (Details)

v3.19.3.a.u2
Mineral Properties - Rollforward (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Sep. 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Balance at beginning of period   $ 45,805 $ 44,677
Acquisition costs   8 31
Change in estimated reclamation costs   11 2,840
Property write-offs   (11)  
Amortization   (2,601) (1,743)
Balance at end of period   43,212 45,805
Lost Creek Project      
Balance at beginning of period   12,644 11,810
Change in estimated reclamation costs   125 2,577
Property write-offs   16  
Amortization   (2,601) (1,743)
Balance at end of period   10,184 12,644
Pathfinder properties      
Balance at beginning of period   19,964 19,701
Change in estimated reclamation costs   (114) 263
Balance at end of period   19,850 19,964
Other U.S. Properties [Member]      
Balance at beginning of period   13,197 13,166
Acquisition costs   8 31
Property write-offs $ (27) (27)  
Balance at end of period   $ 13,178 $ 13,197