Annual report pursuant to Section 13 and 15(d)

ACQUISITIONS (Schedule Of Unaudited Consolidated Proforma Information) (Details)

v2.4.0.8
ACQUISITIONS (Schedule Of Unaudited Consolidated Proforma Information) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2011
Consolidated Thompson [Member]
Dec. 31, 2010
Consolidated Thompson [Member]
Business Acquisition [Line Items]          
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest $ 361.8 $ (1,126.6) $ 1,812.6    
REVENUES FROM PRODUCT SALES AND SERVICES       6,772.3 4,784.6
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS SHAREHOLDERS       $ 1,612.3 $ 912.5
EARNINGS (LOSS) PER COMMON SHARE ATTRIBUTABLE TO CLIFFS SHAREHOLDERS - BASIC       $ 11.50 $ 6.74
EARNINGS (LOSS) PER COMMON SHARE ATTRIBUTABLE TO CLIFFS SHAREHOLDERS - DILUTED       $ 11.43 $ 6.70