ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Narrative) (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Mar. 31, 2018 |
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| Environmental Loss Contingency And Mine Reclamation And Closing Liability Current | $ 3.6 | $ 21.3 |
| Environmental Loss Contingency And Mine Reclamation And Closing Liability Current And Noncurrent | 200.1 | 202.5 |
| U.S. Iron Ore [Member] | Ìý | Ìý |
| Accrual for Environmental Loss Contingencies, Period Increase (Decrease) | (26.2) | Ìý |
| Asia Pacific Iron Ore [Member] | Ìý | Ìý |
| Environmental Loss Contingency And Mine Reclamation And Closing Liability Current | Ìý | $ 17.7 |
| Accrual for Environmental Loss Contingencies, Period Increase (Decrease) | $ (10.1) | Ìý |
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- Definition Environmental Loss Contingency And Mine Reclamation And Closing Liability Current No definition available.
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- Definition Environmental Loss Contingency And Mine Reclamation And Closing Liability Current And Noncurrent No definition available.
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- Definition Increase (decrease) in the accrual for environmental loss contingencies during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Details
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