| INCOME TAXES (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | |
|---|---|---|
| Mar. 31, 2015 | Mar. 31, 2014 | |
| Income Tax Examination [Line Items] | ||
| Income Tax Expense (Benefit) | $ 175.1us-gaap_IncomeTaxExpenseBenefit | $ 29.6us-gaap_IncomeTaxExpenseBenefit | 
| Discrete tax items expense | $ 167.5clf_Discretetaxitemsexpense | |
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- Definition Discrete tax items expense No definition available. 
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- Details 
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- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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