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BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Investments In Unconsolidated Ventures) (Details) - Hibbing [Member] - USD ($)
$ in Millions
Mar. 31, 2016
Dec. 31, 2015
Other Noncurrent Liabilities [Member]    
Schedule of Equity Method Investments [Line Items]    
Equity Method Investments $ 1.7 $ 2.4
Other Noncurrent Assets [Member]    
Schedule of Equity Method Investments [Line Items]    
Ownership interest, equity method investment 23.00%