RELATED PARTIES (Narrative) (Details) $ in Millions |
3 Months Ended | 9 Months Ended |
|---|---|---|
|
Sep. 30, 2017
USD ($)
|
Sep. 30, 2018
USD ($)
Facility
|
|
| Segment Reporting Information [Line Items] | ||
| Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | |
| Purchase of Noncontrolling Interest | $ (105.0) | |
| U.S. Iron Ore [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Number of mines (in number of facilities) | Facility | 4 | |
| Joint Venture Partners [Member] | U.S. Iron Ore [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Number of mines (in number of facilities) | Facility | 1 | |
| Empire | ||
| Segment Reporting Information [Line Items] | ||
| Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | |
| Purchase of Noncontrolling Interest | $ 132.7 | |
| Noncontrolling Interest Purchase, Installment Amount | 44.2 | |
| Other Noncurrent Liabilities [Member] | Empire | ||
| Segment Reporting Information [Line Items] | ||
| Noncontrolling Interest Purchase, Installment Amount | $ 44.2 |
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- Definition Number of mines No definition available.
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- Definition Purchase of Noncontrolling Interest No definition available.
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- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. No definition available.
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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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