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, 2013
Empire [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 79.00%
Tilden [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 85.00%
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] | Tilden [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 0.00%
Arcelor Mittal [Member] | Hibbing [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 62.30%
Arcelor Mittal [Member] | Bloom Lake [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 0.00%
U. S. Steel Canada [Member] | Empire [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 0.00%
U. S. Steel Canada [Member] | Tilden [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 15.00%
U. S. Steel Canada [Member] | Hibbing [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 14.70%
U. S. Steel Canada [Member] | Bloom Lake [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 0.00%
WISCO [Member] | Empire [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 0.00%
WISCO [Member] | Tilden [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 0.00%
WISCO [Member] | Hibbing [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 0.00%
WISCO [Member] | Bloom Lake [Member]
 
Related Party Transaction [Line Items]  
Ownership Interest 25.00%
Equity Method Investments [Member] | Hibbing [Member] | Hibbing [Member]
 
Related Party Transaction [Line Items]  
Ownership interest, equity method investment 23.00% [1]
[1] At December 31, 2012 the classification for Hibbing was Other liabilities.