Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.2
RELATED PARTIES (Summary Of Other Ownership Interests) (Details) - Hibbing [Member]
Jun. 30, 2019
Dec. 31, 2018
Related Party Transaction [Line Items]    
Ownership interest, equity method investment 23.00% 23.00%
Arcelor Mittal [Member]    
Related Party Transaction [Line Items]    
Ownership interest, equity method investment 62.30%  
U. S. Steel Canada [Member]    
Related Party Transaction [Line Items]    
Ownership interest, equity method investment 14.70%