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STOCK COMPENSATION PLANS (Narrative) (Details) (USD $)
In Millions, except Share data, unless otherwise specified |
12 Months Ended | ||
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Dec. 31, 2014
Agreement
Plan
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Dec. 31, 2013
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Dec. 31, 2012
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Plans | 2clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPlans | ||
| Allocated Share-based Compensation Expense | $ 23.7us-gaap_AllocatedShareBasedCompensationExpense | $ 21.1us-gaap_AllocatedShareBasedCompensationExpense | $ 20.6us-gaap_AllocatedShareBasedCompensationExpense |
| Employee Service Share-based Compensation, Tax Benefit from Compensation Expense | 8.3us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense | 7.4us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense | 7.2us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense |
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Plan Year Agreements | 3clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPlanYearAgreements | ||
| Number of performance shares granted | 2,016,996us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod | ||
| Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | 18.3us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized | ||
| Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 2 years 6 months | ||
| Option Indexed to Issuer's Equity, Strike Price | $ 13.83us-gaap_OptionIndexedToIssuersEquityStrikePrice1 | ||
| 2012 Equity Plan [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Number of shares granted under the award |
800,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanMember |
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| Number of performance shares granted |
400,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanMember |
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| Number of restricted shares granted |
300,000us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanMember |
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| 2012 Equity Plan [Member] | Maximum [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Maximum number of shares that may be issued (in shares) |
6,000,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanMember / us-gaap_RangeAxis = us-gaap_MaximumMember |
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| Two Thousand Twelve Equity Plan and Amended Equity Plan [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Performance/vesting period | 3 years | ||
| Payout rate, as a percentage of the original grant |
23.00%clf_ShareBasedGoodsAndNonemployeeServicesTransactionValuationMethodPayoutRate / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanandAmendedEquityPlanMember |
50.00%clf_ShareBasedGoodsAndNonemployeeServicesTransactionValuationMethodPayoutRate / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanandAmendedEquityPlanMember |
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| Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Available for Issuance Proposed to be added to the Plan |
5,000,000clf_SharebasedCompensationArrangementbySharebasedPaymentAwardNumberofAdditionalSharesAvailableforIssuanceProposedtobeaddedtothePlan / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanandAmendedEquityPlanMember |
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| Change in Control [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Allocated Share-based Compensation Expense |
$ 11.7us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis = clf_ChangeinControlMember |
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| Two Thousand Fourteen to Two Thousand Sixteen Performance Period [Member] | Two Thousand Twelve Equity Plan and Amended Equity Plan [Member] | Minimum [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Payout rate, as a percentage of the original grant |
0.00%clf_ShareBasedGoodsAndNonemployeeServicesTransactionValuationMethodPayoutRate / us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis = clf_TwoThousandFourteentoTwoThousandSixteenPerformancePeriodMember / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanandAmendedEquityPlanMember / us-gaap_RangeAxis = us-gaap_MinimumMember |
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| Two Thousand Fourteen to Two Thousand Sixteen Performance Period [Member] | Two Thousand Twelve Equity Plan and Amended Equity Plan [Member] | Maximum [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Payout rate, as a percentage of the original grant |
200.00%clf_ShareBasedGoodsAndNonemployeeServicesTransactionValuationMethodPayoutRate / us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis = clf_TwoThousandFourteentoTwoThousandSixteenPerformancePeriodMember / us-gaap_PlanNameAxis = clf_TwoThousandTwelveEquityPlanandAmendedEquityPlanMember / us-gaap_RangeAxis = us-gaap_MaximumMember |
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- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Available for Issuance Proposed to be added to the Plan No definition available.
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- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Number of Plans No definition available.
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- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Number of Plan Year Agreements No definition available.
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- Definition
Share Based Goods and Nonemployee Services Transaction Valuation Method, Payout Rate No definition available.
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- Definition
Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Unrecognized cost of unvested share-based compensation awards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Exercise or strike price stated in the contract for options indexed to the issuer's equity shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Gross number of share options (or share units) granted during the period. No definition available.
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- Definition
Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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