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PLANT AND EQUIPMENT AND MINERAL PROPERTIES (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Aug. 14, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Property, Plant and Equipment [Line Items]
Abandonment of mineral properties		$ 0	$ 0	$ 0	$ 287
Minimum
Property, Plant and Equipment [Line Items]
Percentage sliding-scale gross proceeds production royalty	6.00%
Maximum
Property, Plant and Equipment [Line Items]
Percentage sliding-scale gross proceeds production royalty	8.00%

X

- Definition

Business Acquisition, Percentage Of Sliding-Scale Gross Proceeds Production Royalty

+ References

No definition available.

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- Definition

The adjustment to expense previously capitalized costs of drilling exploratory wells when proved reserves are not found or when the entity obtains information that raises substantial doubt about the economic or operational viability of the project.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 360
-Section 40
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6475089&loc=d3e66625-109467

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 360
-Section 35
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=66906256&loc=d3e66150-109466

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 360
-Section 40
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6475089&loc=d3e66584-109467

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 360
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6475089&loc=d3e66610-109467

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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