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QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) QUARTERLY RESULTS OF OPERATIONS (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified |
3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Dec. 31, 2013
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Mar. 31, 2013
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2013
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
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Dec. 31, 2013
Wabush [Member]
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Dec. 31, 2012
Wabush [Member]
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Dec. 31, 2012
CQIM Reporting Unit [Member]
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Dec. 31, 2012
Deferred Tax Asset, MRRT Starting Base [Member]
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Dec. 31, 2012
Deferred Tax Asset, Alternative Minimum Tax Credit Not Utilized [Member]
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Dec. 31, 2013
Bloom Lake [Member]
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Dec. 31, 2012
Bloom Lake [Member]
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Sep. 30, 2012
Bloom Lake [Member]
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Jun. 30, 2012
Bloom Lake [Member]
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Mar. 31, 2012
Bloom Lake [Member]
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Dec. 31, 2013
Bloom Lake [Member]
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Dec. 31, 2012
Bloom Lake [Member]
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Dec. 31, 2011
Bloom Lake [Member]
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| Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 45.1 | Ìý | Ìý |
| Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | 25.2 | 12.9 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Noncontrolling Interest, Ownership Percentage by Parent | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 82.80% | 75.00% | Ìý | Ìý | Ìý | 82.80% | 75.00% | Ìý |
| Goodwill, Impairment Loss | Ìý | Ìý | 80.9 | 1,000.0 | Ìý | 80.9 | Ìý | 2.7 | 997.3 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Asset Impairment Charges | Ìý | Ìý | 250.8 | 1,049.9 | 27.8 | Ìý | 154.6 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Impairment of Long-Lived Assets Held-for-use | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 140.1 | 49.9 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Income Tax Expense (Benefit) | Ìý | Ìý | $ 55.1 | $ 255.9 | $ 407.7 | Ìý | Ìý | Ìý | Ìý | $ 314.7 | $ 226.4 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Change in Basic EPS for Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 0.29 | $ 0.04 | $ 0.04 | $ 0.03 | $ 0.14 | $ 0.30 | $ 0 | $ 0.07 |
| Change in Diluted EPS for Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 0.29 | $ 0.04 | $ 0.04 | $ 0.03 | $ 0.14 | $ 0.26 | $ 0.25 | $ 0.07 |
| X | ||||||||||
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- Definition
Change in Basic EPS for Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition No definition available.
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| X | ||||||||||
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- Definition
Change in Diluted EPS for Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition No definition available.
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| X | ||||||||||
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- Definition
Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition No definition available.
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| X | ||||||||||
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- Definition
Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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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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