Annual report pursuant to Section 13 and 15(d)

Environmental And Mine Closure Obligations (Narrative) (Details)

v2.4.0.6
Environmental And Mine Closure Obligations (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2011
Allocation Agreement [Member]
Dec. 31, 2010
Allocation Agreement [Member]
May 29, 2009
Allocation Agreement [Member]
Dec. 31, 2011
Previously Owned Or Operating Facilities [Member]
L T V Steel Mining Company [Member]
Dec. 31, 2010
Previously Owned Or Operating Facilities [Member]
L T V Steel Mining Company [Member]
Loss Contingencies [Line Items]              
Payments related to environmental and mine closure liabilities $ 1.9 $ 10.6          
Environmental Obligation Funding Percentage         32.50%    
Allocation agreement, commited remedy, percent         32.50%    
Environmental liabilities 15.5 13.7 10.0 9.2      
Estimated costs of the available remediation alternatives minimum amount 10.0            
Estimated costs of the available remediation alternatives maximum amount 30.5            
Mine closure obligation 220.2 185.4       16.5 17.1
Rate of inflation 3.50%            
Total environmental and mine closure obligations $ 235.7 $ 199.1