Quarterly report pursuant to Section 13 or 15(d)

DISCONTINUED OPERATIONS PreTax Exit Costs (Details)

v2.4.1.9
DISCONTINUED OPERATIONS PreTax Exit Costs (Details) (Canadian Entities [Member], USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Canadian Entities [Member]
   
PreTax Exit Costs [Line Items]    
Investment Impairment on Deconsolidation $ (476.0)clf_InvestmentImpairmentonDeconsolidation
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= clf_CanadianEntitiesMember
 
Contingent Liabilities (342.7)clf_ContingentLiabilities
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= clf_CanadianEntitiesMember
 
Business Exit Costs $ (818.7)us-gaap_BusinessExitCosts1
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$ 0us-gaap_BusinessExitCosts1
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