PROPERTY, PLANT AND EQUIPMENT - Net Book Value of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment	$ 8,985	$ 20,337
(Less) property, plant and equipment included in assets held for sale		(11,342)
Net property, plant and equipment	8,985	8,995
Texas
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment		3,536
(Less) property, plant and equipment included in assets held for sale		(3,536)
Alabama
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment	8,972	8,972
Net property, plant and equipment		8,972
New Mexico
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment		7,806
(Less) property, plant and equipment included in assets held for sale		(7,806)
Net property, plant and equipment		0
Corporate
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment	13	23
Net property, plant and equipment		23
Uranium plant
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment		3,112
Uranium plant | Texas
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment		3,112
Mineral rights and properties
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment	8,972	16,778
Mineral rights and properties | Alabama
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment	8,972	8,972
Mineral rights and properties | New Mexico
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment		7,806
Other property, plant and equipment
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment	13	447
Other property, plant and equipment | Texas
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment		424
Other property, plant and equipment | Corporate
Property, Plant and Equipment [Line Items]
Total Property, Plant and Equipment	$ 13	$ 23