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STOCK COMPENSATION PLANS (Assumptions Utilized To Estimate Fair Value For Performance Share Grants) (Details) (Performance Shares [Member], USD $)
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3 Months Ended |
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Mar. 31, 2015
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| January 12, 2015 [Member] | |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
| Grant Date Market Price |
$ 7.70clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantDatePrice / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Average Expected Term (Years) | 2 years 11 months 20 days |
| Expected Volatility |
58.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Risk-Free Interest Rate |
0.91%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Dividend Yield |
0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Fair Value |
$ 11.56us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Fair Value (Percent of Grant Date Market Price) |
150.13%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate / us-gaap_AwardDateAxis = clf_January122015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| February 9, 2015 [Member] | |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
| Grant Date Market Price |
$ 6.57clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantDatePrice / us-gaap_AwardDateAxis = clf_February92015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Average Expected Term (Years) | 2 years 10 months 20 days |
| Expected Volatility |
58.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate / us-gaap_AwardDateAxis = clf_February92015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Risk-Free Interest Rate |
0.87%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardDateAxis = clf_February92015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Dividend Yield |
0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardDateAxis = clf_February92015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Fair Value |
$ 9.86us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardDateAxis = clf_February92015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
| Fair Value (Percent of Grant Date Market Price) |
150.13%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate / us-gaap_AwardDateAxis = clf_February92015Member / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |
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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
Discount rate from fair value on offering date that participants pay for shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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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