PROPERTY, PLANT AND EQUIPMENT - Schedule of Mineral Property Expenses (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($) project	Dec. 31, 2018 USD ($) project
Exploration and evaluation costs, amounts spent	$ 2,852	$ 3,538
Temrezli Project, Turkey
Exploration and evaluation costs, amounts spent		117
Total Turkey Projects
Exploration and evaluation costs, amounts spent		117
Kingsville Dome Project, Texas
Exploration and evaluation costs, amounts spent	716	800
Rosita Project, Texas
Exploration and evaluation costs, amounts spent	530	738
Vasquez Project, Texas
Exploration and evaluation costs, amounts spent	495	631
Other Projects, Texas
Exploration and evaluation costs, amounts spent		20
Exploration and evaluation costs (reversals)	(4)
Total Texas Projects
Exploration and evaluation costs, amounts spent	$ 1,737	$ 2,189
South Texas ISR projects
Number of idled projects \| project	3	3
Cebolleta Project, New Mexico
Exploration and evaluation costs, amounts spent	$ 440	$ 389
Juan Tafoya Project, New Mexico
Exploration and evaluation costs, amounts spent	223	223
Other Projects, New Mexico
Exploration and evaluation costs, amounts spent	13
Total New Mexico Projects
Exploration and evaluation costs, amounts spent	676	612
Columbus Basin Project, Nevada
Exploration and evaluation costs, amounts spent	126	249
Other projects, Nevada
Exploration and evaluation costs, amounts spent		90
Total Nevada Projects
Exploration and evaluation costs, amounts spent	126	339
Sal Rica Project, Utah
Exploration and evaluation costs, amounts spent	111	141
Total Utah Projects
Exploration and evaluation costs, amounts spent	111	141
Coosa Project, Alabama
Exploration and evaluation costs, amounts spent	202	140
Total Alabama Projects
Exploration and evaluation costs, amounts spent	$ 202	$ 140