DESCRIPTION OF BUSINESS - Purchase Commitment excluding Long-term Commitment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 09, 2019	Apr. 17, 2015	Dec. 31, 2014
Cash commitments
Face amount					$ 8,500
Amount committed to be purchased	$ 600
Restricted cash held at EMLLC	3,388	$ 6,167
Purchase Commitment | Mining and milling equipment | Eureka Moly LLC
Cash commitments
Aggregate amount of equipment orders	88,000
Amount of equipment orders relate to fully fabricated items	71,700
Amount of equipment orders relate to partially fabricated milling equipment, and non-refundable deposits on mining equipment	16,300
Mt. Hope Project
Cash commitments
Balance of reserve account	3,400	6,200
Restricted cash held at EMLLC	3,400	$ 6,200
Mt. Hope Project | Eureka Moly LLC
Cash commitments
Aggregate amount of equipment orders	$ 88,000
Senior secured term loan | Mt. Hope Project | AMER International Group
Cash commitments
Face amount			$ 700,000	$ 700,000