BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Equity Method Investments) (Details) (Details)	Mar. 31, 2020
Combined Metals of Chicago, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	40.00%
Hibbing Taconite Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	23.00%
Spartan Steel Coating, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	48.00%