Annual report pursuant to Section 13 and 15(d)

Mineral Properties - rollforward (Details)

v3.8.0.1
Mineral Properties - rollforward (Details) - USD ($)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Balance at beginning of period $ 47,029,000 $ 50,610,000
Acquisition costs 18,000  
Change in estimated reclamation costs (Note 13) 448,000 (534,000)
Write-off of mineral properties (note 7)   (62,000)
Amortization (2,818,000) (2,985,000)
Balance at end of period 44,677,000 47,029,000
Lost Creek Property    
Balance at beginning of period 14,015,000 16,662,000
Change in estimated reclamation costs (Note 13) 613,000 338,000
Amortization (2,818,000) (2,985,000)
Balance at end of period 11,810,000 14,015,000
Path Finder Mines [Member]    
Balance at beginning of period 19,866,000 20,738,000
Change in estimated reclamation costs (Note 13) (165,000) (872,000)
Balance at end of period 19,701,000 19,866,000
Other U.S. Properties [Member]    
Balance at beginning of period 13,148,000 13,210,000
Acquisition costs 18,000  
Write-off of mineral properties (note 7)   (62,000)
Balance at end of period $ 13,166,000 $ 13,148,000