SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Property, Plant and Equipment) (Details)	12 Months Ended
	Dec. 31, 2019
Building
Property, Plant and Equipment [Line Items]
Property, plant, equipment and mine development, useful life	50 years
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant, equipment and mine development, useful life	3 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant, equipment and mine development, useful life	50 years