PLANT AND EQUIPMENT AND CONSTRUCTION IN PROGRESS - Construction-in-progress (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Construction in progress
Construction-in-progress	$ 74,643	$ 8,178
Gold Bar project
Construction in progress
Construction-in-progress	72,425	6,011
Black Fox
Construction in progress
Construction-in-progress	118	67
Fenix Project Properties
Construction in progress
Construction-in-progress	$ 2,100	$ 2,100

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Name:	us-gaap_ConstructionInProgressGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant