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STOCK COMPENSATION PLANS Stock Option Activity (Details) (Employee Stock Option [Member], January 12, 2015 [Member], USD $)
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3 Months Ended |
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Mar. 31, 2015
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Employee Stock Option [Member] | January 12, 2015 [Member]
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| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | |
| Share Based Compensation Arrangement By Share Based Payment Award Grant Date Price |
$ 7.70clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantDatePrice / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |
| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term | 6 years 5 months 20 days |
| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate |
75.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |
| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate |
1.60%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |
| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate |
0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |
| Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value |
$ 5.23us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |
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- Definition
Share Based Compensation Arrangement by Share Based Payment Award Grant Date Price No definition available.
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- Definition
The weighted average fair value at grant date for nonvested equity-based awards issued 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 estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Expected term of share-based compensation awards, 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 estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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