Annual report pursuant to Section 13 and 15(d)

Quarterly Results Of Operations (Schedule Of Error Corrections And Prior Period Adjustments) (Details)

v2.4.0.6
Quarterly Results Of Operations (Schedule Of Error Corrections And Prior Period Adjustments) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified
3 Months Ended 12 Months Ended 3 Months Ended 6 Months Ended
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Mar. 31, 2011
Dec. 31, 2010
Sep. 30, 2010
Jun. 30, 2010
Mar. 31, 2010
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Jun. 30, 2011
Empire [Member]
Mar. 31, 2011
Empire [Member]
Jun. 30, 2011
Empire [Member]
Related Party Transaction [Line Items]                            
Product                 $ 6,551.7 $ 4,416.8 $ 2,216.2 $ 46.0 $ 54.1 $ 100.1
Freight and venture partners' cost reimbursements                 242.6 265.3 125.8 (46.0)   (46.0)
Revenues from product sales and services 1,662.5 2,142.8 1,805.8 1,183.2 1,424.1 1,346.0 1,184.3 727.7 6,794.3 4,682.1 2,342.0   54.1 54.1
Cost of Goods Sold and Operating Expenses                 4,105.7 3,155.6 2,030.3   (54.1) (54.1)
Income from Continuing Operations                 2,348.6 1,270.2 236.1 7.7 8.4 16.1
LESS: NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTEREST                 193.5     38.1 45.9 84.0
Net Income Attributable to Cliffs Shareholders $ 185.4 $ 601.2 $ 409.1 $ 423.4 $ 384.1 $ 297.6 $ 260.8 $ 77.4 $ 1,619.1 $ 1,019.9 $ 205.1 $ (30.4) $ (37.5) $ (67.9)
Earnings Per Share [Abstract]                            
Earnings Per Share, Basic and Diluted                       $ (0.22) $ (0.28) $ (0.49)