BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) - Hibbing [Member] - USD ($) $ in Millions |
Jun. 30, 2018 |
Dec. 31, 2017 |
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| Other Noncurrent Assets [Member] | ||
| Related Party Transaction [Line Items] | ||
| Ownership interest, equity method investment | 23.00% | 23.00% |
| Other Noncurrent Liabilities [Member] | ||
| Related Party Transaction [Line Items] | ||
| Equity Method Investments | $ 8.0 | $ 11.0 |
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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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