Quarterly report pursuant to Section 13 or 15(d)

Related Parties (Summary Of Other Ownership Interests) (Details)

v2.4.0.6
Related Parties (Summary Of Other Ownership Interests) (Details)
Mar. 31, 2012
Mar. 31, 2011
Empire [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 79.00% 79.00%
Tilden [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 85.00% 85.00%
Bloom Lake [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 75.00% 75.00%
Cliffs Natural Resources [Member] | Empire [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 79.00%  
Cliffs Natural Resources [Member] | Tilden [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 85.00%  
Cliffs Natural Resources [Member] | Hibbing [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 23.00%  
Cliffs Natural Resources [Member] | Bloom Lake [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 75.00%  
Arcelor Mittal [Member] | Empire [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 21.00%  
Arcelor Mittal [Member] | Hibbing [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 62.30%  
U. S. Steel Canada | Tilden [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 15.00%  
U. S. Steel Canada | Hibbing [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 14.70%  
WISCO [Member] | Bloom Lake [Member]
   
Related Party Transaction [Line Items]    
Ownership Interest 25.00%