ACQUISITION (Details) $ in Thousands	1 Months Ended		6 Months Ended
	Nov. 30, 2019 USD ($)	Aug. 31, 2019 USD ($) payment shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Aug. 31, 2019 $ / shares	Jun. 30, 2019 USD ($)
Acquisitions
Acquisition consideration paid			$ 72,417	$ 55
Investment value			$ 15,200			$ 16,000
TriStar
Acquisitions
Common stock that can be purchased by warrants (in shares) | shares			15,712,000
CDS
Acquisitions
Net smelter return (NSR) (as a percent)		1.50%
Acquisition consideration		$ 7,500
Number of installments | payment		3
Acquisition consideration paid	$ 1,500	$ 4,500
Second installment		1,500
Acquisition payment, excluding associated costs		$ 6,000
CDS | TriStar
Acquisitions
Common stock that can be purchased by warrants (in shares) | shares		19,640,000	15,712,000
Investment value			$ 200
Exercise price of warrants | $ / shares					$ 0.25
Term of warrants			5 years