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PROPERTY, PLANT AND EQUIPMENT (Narrative) (Details) (USD $)
In Millions, unless otherwise specified |
12 Months Ended | ||
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Property, Plant and Equipment [Line Items] | |||
| Depletion | $ 173.0us-gaap_Depletion | $ 206.5us-gaap_Depletion | $ 209.8us-gaap_Depletion |
| Depreciation | 320.6us-gaap_Depreciation | 366.9us-gaap_Depreciation | 293.5us-gaap_Depreciation |
| Document Fiscal Year Focus | 2014 | ||
| Tangible Asset Impairment Charges | 8,839.0us-gaap_TangibleAssetImpairmentCharges | ||
| Construction in Progress [Member] | |||
| Property, Plant and Equipment [Line Items] | |||
| Accumulated amount of capitalized interest included within construction in progress |
31.4us-gaap_AccumulatedCapitalizedInterestCosts / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_ConstructionInProgressMember |
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| Interest costs capitalized during the period |
17.4us-gaap_InterestCostsCapitalized / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_ConstructionInProgressMember |
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| Wabush [Member] | |||
| Property, Plant and Equipment [Line Items] | |||
| Tangible Asset Impairment Charges |
145.1us-gaap_TangibleAssetImpairmentCharges / clf_ReportingUnitAxis = clf_WabushMember |
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| Impairment of Long-Lived Assets Held-for-use |
140.1us-gaap_ImpairmentOfLongLivedAssetsHeldForUse / clf_ReportingUnitAxis = clf_WabushMember |
49.9us-gaap_ImpairmentOfLongLivedAssetsHeldForUse / clf_ReportingUnitAxis = clf_WabushMember |
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| Land Rights And Mineral Rights [Member] | |||
| Property, Plant and Equipment [Line Items] | |||
| Tangible Asset Impairment Charges |
$ 5,772.7us-gaap_TangibleAssetImpairmentCharges / us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis = us-gaap_MiningPropertiesAndMineralRightsMember |
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| X | ||||||||||
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- Definition
This is focus fiscal year of the document report in CCYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006. No definition available.
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- Definition
Amount of accumulated interest costs capitalized as part of property, plant and equipment cost basis. No definition available.
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- Definition
The noncash expense charged against earnings to recognize the consumption of natural resources. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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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- Definition
Amount of interest capitalized during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Details
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