| GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Earnings To Be Recognized On Below Market Sales Contract) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 
|---|---|
| Mar. 31, 2015 | |
| Estimated recognition of product revenues, below-market sales contracts [Abstract] | |
| 2015 (remaining nine months) | $ 23.0clf_FutureBelowMarketSalesContractsRevenueRemainderofCurrentYear | 
| 2016 | 23.1clf_FutureBelowMarketSalesContractsRevenueYearOne | 
| Total | $ 46.1clf_FutureBelowMarketSalesContractsRevenueWithinFiveYears | 
| X | ||||||||||
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- Definition Future Below Market Sales Contracts Revenue, Remainder of Current Year No definition available. 
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| X | ||||||||||
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- Definition Future Below Market Sales Contracts Revenue, Within Five Years No definition available. 
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| X | ||||||||||
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- Definition Future Below Market Sales Contracts Revenue, Year One No definition available. 
 | 
| X | ||||||||||
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- Details 
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