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INCOME TAXES INCOME TAXES (Schedule of Unrecognized Tax Benefits Rollforward) (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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Dec. 31, 2010
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| Income Tax Contingency [Line Items] | ||||
| Unrecognized Tax Benefits | $ 74.7us-gaap_UnrecognizedTaxBenefits | $ 74.4us-gaap_UnrecognizedTaxBenefits | $ 55.5us-gaap_UnrecognizedTaxBenefits | $ 102.1us-gaap_UnrecognizedTaxBenefits |
| Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions | 3.4us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions | 13.6us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions | 2.7us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions | |
| Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions | 2.5us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions | 5.3us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions | 11.1us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions | |
| Unrecognized Tax Benefits Increases Decreases Resulting From Currency Translation | (0.2)clf_UnrecognizedTaxBenefitsIncreasesDecreasesResultingFromCurrencyTranslation | 0clf_UnrecognizedTaxBenefitsIncreasesDecreasesResultingFromCurrencyTranslation | 0clf_UnrecognizedTaxBenefitsIncreasesDecreasesResultingFromCurrencyTranslation | |
| Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities | (0.5)us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities | 0us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities | (60.4)us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities | |
| Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations | (3.7)us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations | 0us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations | 0us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations | |
| Other Increases decreases to unrecognized tax benefits | $ (1.2)clf_OtherIncreasesDecreasesToUnrecognizedTaxBenefits | $ 0clf_OtherIncreasesDecreasesToUnrecognizedTaxBenefits | $ 0clf_OtherIncreasesDecreasesToUnrecognizedTaxBenefits | |
| X | ||||||||||
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- Definition
Other Increases decreases to unrecognized tax benefits No definition available.
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- Definition
The gross amount of increases in unrecognized tax benefits resulting from currency translation. No definition available.
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- Details
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| X | ||||||||||
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- Definition
Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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