Quarterly report pursuant to Section 13 or 15(d)

Basis Of Presentation And Significant Accounting Policies (Significant Consolidated Subsidiaries) (Details)

v2.3.0.15
Basis Of Presentation And Significant Accounting Policies (Significant Consolidated Subsidiaries) (Details)
 9 Months Ended
Sep. 30, 2011
Northshore [Member]
  
Location Minnesota
Ownership Interest 100.00%
Operation Iron Ore
United Taconite [Member]
  
Location Minnesota
Ownership Interest 100.00%
Operation Iron Ore
Wabush [Member]
  
Location Labrador/Quebec, Canada
Ownership Interest 100.00%
Operation Iron Ore
Bloom Lake [Member]
  
Location Quebec, Canada
Ownership Interest 75.00%
Operation Iron Ore
Tilden [Member]
  
Location Michigan
Ownership Interest 85.00%
Operation Iron Ore
Empire [Member]
  
Location Michigan
Ownership Interest 79.00%
Operation Iron Ore
Asia Pacific Iron Ore [Member]
  
Location Western Australia
Ownership Interest 100.00%
Operation Iron Ore
Pinnacle [Member]
  
Location West Virginia
Ownership Interest 100.00%
Operation Coal
Oak Grove [Member]
  
Location Alabama
Ownership Interest 100.00%
Operation Coal
CLCC [Member]
  
Location West Virginia
Ownership Interest 100.00%
Operation Coal
RenewaFUEL [Member]
  
Location Michigan [1]
Ownership Interest 95.00% [1]
Operation Biomass [1]
Freewest [Member]
  
Location Ontario, Canada
Ownership Interest 100.00%
Operation Chromite
Spider [Member]
  
Location Ontario, Canada
Ownership Interest 100.00%
Operation Chromite
[1] On September 27, 2011, we announced our plans to cease the operations of renewaFUEL. See the Discontined Operations disclosure below for further details.