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MINERAL PROPERTY INTERESTS - Mineral Property Interests (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2018 | Mar. 31, 2017 | Dec. 31, 2017 | Aug. 25, 2017
Mineral Property Interests |  |  |  |
Mineral property interests | $ 296,034 |  | $ 293,437 |
Payments to Acquire Mining Assets | 4,084 |  |  |
Amortization of mineral property interests and asset retirement obligations | 1,800 | $ 533 |  |
El Gallo 1 mine |  |  |  |
Mineral Property Interests |  |  |  |
Amortization of mineral property interests and asset retirement obligations | 800 | $ (500) |  |
Black Fox |  |  |  |
Mineral Property Interests |  |  |  |
Mineral property interests |  |  |  | $ 8,954
Amortization of mineral property interests and asset retirement obligations | $ 2,700 |  | $ 0 |

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- Definition Represents the amount of amortization expense related to the mineral property interests and capitalized asset retirement costs. + References No definition available. + Details
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Balance Type: | debit
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- Definition Mineral Property Interests [Line Items] + References No definition available. + Details
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- Definition Mineral properties, net of adjustments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 25 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=96866604&loc=d3e64895-109465 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
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- Definition The cash outflow from the purchase of mining and mining related assets during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585 + Details
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- Details
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- Details
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Period Type: |