Mineral Properties - rollforward (Details) - USD ($) $ in Thousands |
9 Months Ended | 12 Months Ended |
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Sep. 30, 2018 |
Dec. 31, 2017 |
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Balance at beginning of period | $ 44,677 | |
Acquisition costs | 31 | |
Increase in reclamation costs | 34 | |
Change in estimated reclamation costs (Note 13) | 34 | $ 448 |
Amortization | (1,307) | |
Balance at end of period | 43,435 | 44,677 |
Lost Creek Property | ||
Balance at beginning of period | 11,810 | |
Increase in reclamation costs | 34 | |
Amortization | (1,307) | |
Balance at end of period | 10,537 | 11,810 |
Path Finder Mines [Member] | ||
Balance at beginning of period | 19,701 | |
Balance at end of period | 19,701 | 19,701 |
Other U.S. Properties [Member] | ||
Balance at beginning of period | 13,166 | |
Acquisition costs | 31 | |
Balance at end of period | $ 13,197 | $ 13,166 |
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- Definition The assumption amount in estimated asset reclamation obligation. No definition available.
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- Definition The capitalized costs incurred during the period (excluded from amortization) to purchase, lease or otherwise acquire an unproved property, including costs of lease bonuses and options to purchase or lease properties, the portion of costs applicable to minerals when land including mineral rights is purchased in fee, brokers' fees, recording fees, legal costs, and other costs incurred in acquiring properties. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Mineral properties, net of adjustments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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