PROPERTY, PLANT AND EQUIPMENT - Net Book Value of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	$ 144,427	$ 143,193
Mineral rights and properties
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	8,972	8,972
Buildings
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	3,093	3,122
Other property, plant and equipment
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	4,211	4,370
Construction in progress
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	128,151	126,729
Alabama
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	144,418	143,183
Alabama \| Mineral rights and properties
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	8,972	8,972
Alabama \| Buildings
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	3,093	3,122
Alabama \| Other property, plant and equipment
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	4,202	4,360
Alabama \| Construction in progress
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	128,151	126,729
Corporate
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	9	10
Corporate \| Other property, plant and equipment
PROPERTY, PLANT AND EQUIPMENT
Total Property, Plant and Equipment	$ 9	$ 10