Annual report pursuant to Section 13 and 15(d)

INVENTORIES (Schedule Of Inventories) (Details)

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INVENTORIES (Schedule Of Inventories) (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Inventory, Net [Abstract]    
Finished Goods $ 160.4 $ 148.0
Work-in Process 23.0 30.4
Total Inventory 183.4 178.4
U.S. Iron Ore [Member]    
Inventory, Net [Abstract]    
Finished Goods 127.1 124.4
Work-in Process 11.3 12.6
Total Inventory 138.4 137.0
Asia Pacific Iron Ore [Member]    
Inventory, Net [Abstract]    
Finished Goods 33.3 23.6
Work-in Process 11.7 17.8
Total Inventory $ 45.0 $ 41.4