Quarterly report pursuant to Section 13 or 15(d)

Acquisitions and Other Investments (Freewest Purchase Price Allocation) (Details)

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Acquisitions and Other Investments (Freewest Purchase Price Allocation) (Details) (USD $)
In Millions
Dec. 31, 2010
Mar. 31, 2010
Scenario, Previously Reported [Member]
Freewest [Member]
Mar. 31, 2010
Freewest [Member]
Dec. 31, 2009
Freewest [Member]
Equity instruments (4.2 million Cliffs common shares)   $ 173.1    
Cash   12.8    
Fair value of Cliffs' equity interest in acquiree held prior to acquisition of remaining interest       27.4
Total net assets acquired 1.7   185.9  
Total net assets acquired $ 1.7   $ 185.9