Quarterly report pursuant to Section 13 or 15(d)

INVENTORIES (Schedule Of Inventories) (Details)

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INVENTORIES (Schedule Of Inventories) (Details) - USD ($)
$ in Millions
Sep. 30, 2017
Dec. 31, 2016
Inventory, Net [Abstract]    
Finished Goods $ 180.7 $ 148.0
Work-in Process 27.0 30.4
Total Inventory 207.7 178.4
U.S. Iron Ore [Member]    
Inventory, Net [Abstract]    
Finished Goods 151.3 124.4
Work-in Process 18.6 12.6
Total Inventory 169.9 137.0
Asia Pacific Iron Ore [Member]    
Inventory, Net [Abstract]    
Finished Goods 29.4 23.6
Work-in Process 8.4 17.8
Total Inventory $ 37.8 $ 41.4