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BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | ||
|---|---|---|---|
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Mar. 31, 2015
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Mar. 31, 2014
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Dec. 31, 2014
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| Related Party Transaction [Line Items] | Ìý | Ìý | Ìý |
| Unamortized Debt Issuance Expense | $ 46.2us-gaap_UnamortizedDebtIssuanceExpense | Ìý | $ 25.6us-gaap_UnamortizedDebtIssuanceExpense |
| Derivative, Policy, Percentage of Amount Permitted to be Hedged | 75.00%clf_DerivativePolicyPercentageOfAmountPermittedToBeHedged | Ìý | Ìý |
| Current Fiscal Year End Date | --12-31 | Ìý | Ìý |
| Derivative, Policy, Minimum Percentage of Amount Permitted to be Hedged for Derivatives with Periods of up to Twelve Months | 40.00%clf_DerivativePolicyMinimumPercentageOfAmountPermittedToBeHedgedForDerivativesWithPeriodsOfUpToTwelveMonths | Ìý | Ìý |
| Derivative, Policy, Minimum Percentage of Amount Permitted to be Hedged for Derivatives with Periods of up to Fifteen Months | 10.00%clf_DerivativePolicyMinimumPercentageOfAmountPermittedToBeHedgedForDerivativesWithPeriodsOfUpToFifteenMonths | Ìý | Ìý |
| Transaction Gains and Losses Resulting from Remeasurement [Member] | Ìý | Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý | Ìý |
| Foreign Currency Transaction Gain (Loss), before Tax |
13.5us-gaap_ForeignCurrencyTransactionGainLossBeforeTax / us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis = clf_TransactionGainsandLossesResultingfromRemeasurementMember |
(11.4)us-gaap_ForeignCurrencyTransactionGainLossBeforeTax / us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis = clf_TransactionGainsandLossesResultingfromRemeasurementMember |
Ìý |
| Short-term intercompany loan [Member] | Ìý | Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý | Ìý |
| Foreign Currency Transaction Gain (Loss), before Tax |
12.4us-gaap_ForeignCurrencyTransactionGainLossBeforeTax / us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis = clf_ShorttermintercompanyloanMember |
(8.8)us-gaap_ForeignCurrencyTransactionGainLossBeforeTax / us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis = clf_ShorttermintercompanyloanMember |
Ìý |
| Cash and Cash Equivalents [Member] | Ìý | Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý | Ìý |
| Foreign Currency Transaction Gain (Loss), before Tax |
$ 1.5us-gaap_ForeignCurrencyTransactionGainLossBeforeTax / us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis = us-gaap_CashAndCashEquivalentsMember |
$ (3.1)us-gaap_ForeignCurrencyTransactionGainLossBeforeTax / us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis = us-gaap_CashAndCashEquivalentsMember |
Ìý |
| X | ||||||||||
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- Definition
Derivative, Policy, Minimum Percentage of Amount Permitted to be Hedged for Derivatives with Periods of up to Fifteen Months No definition available.
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- Definition
Derivative, Policy, Minimum Percentage of Amount Permitted to be Hedged for Derivatives with Periods of up to Twelve Months No definition available.
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| X | ||||||||||
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- Definition
Derivative, Policy, Percentage of Amount Permitted to be Hedged No definition available.
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| X | ||||||||||
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- Definition
End date of current fiscal year in the format --MM-DD. No definition available.
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- Definition
Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Details
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- Details
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