LIQUIDITY - Purchase Commitment excluding Long-term Commitment (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Apr. 17, 2015	Dec. 31, 2014
Cash commitments
Face amount				$ 8,500
Restricted cash held at EMLLC	$ 12,016	$ 13,025
Amount committed to be purchased	2,200
Restricted Cash Held by Limited Liability Corporation	12,016	13,025
Per month reduction in non-equipment related cash requirements	1,500
Purchase Commitment | Nevada Moly LLC | POS-Minerals Corporation
Cash commitments
Amount funded to reserve account	36,000
Purchase Commitment | Mining and milling equipment | Eureka Moly LLC
Cash commitments
Aggregate amount of equipment orders	87,400
Amount of equipment orders relate to fully fabricated items	70,400
Amount of equipment orders relate to partially fabricated milling equipment, and non-refundable deposits on mining equipment	17,000
Mt. Hope Project
Cash commitments
Balance of reserve account	12,000	$ 13,000
Mt. Hope Project | AMER International Group
Cash commitments
Amount committed to be purchased			$ 16,500
Mt. Hope Project | Eureka Moly LLC
Cash commitments
Aggregate amount of equipment orders	87,400
Senior secured term loan | Mt. Hope Project | AMER International Group
Cash commitments
Face amount	700,000		$ 700,000
Proceeds from equity investment	$ 16,000