Quarterly report pursuant to Section 13 or 15(d)

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Summary Of Mine Closure Obligations) (Details)

v2.4.0.8
ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Summary Of Mine Closure Obligations) (Details) (USD $)
In Millions, unless otherwise specified
Sep. 30, 2014
Dec. 31, 2013
Loss Contingencies [Line Items]    
Environmental $ 5.6 $ 8.4
Mine Reclamation and Closing Liability, current and noncurrent 305.1 312.6
Total environmental and mine closure obligations 310.7 321.0
Less current portion 5.3 11.3
Long term environmental and mine closure obligations 305.4 309.7
U.S. Iron Ore [Member] | Owned Or Operating Facilities [Member]
    
Loss Contingencies [Line Items]    
Mine Reclamation and Closing Liability, current and noncurrent 138.5 152.2
Eastern Canadian Iron Ore [Member] | Owned Or Operating Facilities [Member]
    
Loss Contingencies [Line Items]    
Mine Reclamation and Closing Liability, current and noncurrent 81.9 78.2
Asia Pacific Iron Ore [Member] | Owned Or Operating Facilities [Member]
    
Loss Contingencies [Line Items]    
Mine Reclamation and Closing Liability, current and noncurrent 25.8 25.5
North American Coal [Member] | Owned Or Operating Facilities [Member]
    
Loss Contingencies [Line Items]    
Mine Reclamation and Closing Liability, current and noncurrent 36.2 34.7
LTV Steel Mining Company [Member] | Previously Owned Or Operating Facilities [Member]
    
Loss Contingencies [Line Items]    
Mine Reclamation and Closing Liability, current and noncurrent $ 22.7 $ 22.0