Annual report pursuant to Section 13 and 15(d)

RELATED PARTIES (Summary Of Other Ownership Interests) (Details)

v2.4.0.8
RELATED PARTIES (Summary Of Other Ownership Interests) (Details)
Dec. 31, 2013
Dec. 31, 2012
Hibbing [Member] | Arcelor Mittal [Member]
   
Related Party Transaction [Line Items]    
Ownership interest, equity method investment 62.30%  
Hibbing [Member] | WISCO [Member]
   
Related Party Transaction [Line Items]    
Ownership interest, equity method investment 0.00%  
Hibbing [Member] | U. S. Steel Canada [Member]
   
Related Party Transaction [Line Items]    
Ownership interest, equity method investment 14.70%  
Empire [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Parent 79.00%  
Empire [Member] | Arcelor Mittal [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 21.00%  
Empire [Member] | WISCO [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 0.00%  
Empire [Member] | U. S. Steel Canada [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 0.00%  
Tilden [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Parent 85.00%  
Tilden [Member] | Arcelor Mittal [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 0.00%  
Tilden [Member] | WISCO [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 0.00%  
Tilden [Member] | U. S. Steel Canada [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 15.00%  
Bloom Lake [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Parent 82.80% 75.00%
Bloom Lake [Member] | Arcelor Mittal [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 0.00%  
Bloom Lake [Member] | WISCO [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 17.20%  
Bloom Lake [Member] | U. S. Steel Canada [Member]
   
Related Party Transaction [Line Items]    
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 0.00%  
Investments in Ventures [Member] | Hibbing [Member]
   
Related Party Transaction [Line Items]    
Ownership interest, equity method investment 23.00%