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
Mar. 31, 2016
Dec. 31, 2015
Inventory, Net [Abstract]    
Finished Goods $ 334.4 $ 273.1
Work-in Process 71.9 56.5
Total Inventory 406.3 329.6
U.S. Iron Ore [Member]    
Inventory, Net [Abstract]    
Finished Goods 312.3 252.3
Work-in Process 25.0 11.7
Total Inventory 337.3 264.0
Asia Pacific Iron Ore [Member]    
Inventory, Net [Abstract]    
Finished Goods 22.1 20.8
Work-in Process 46.9 44.8
Total Inventory $ 69.0 $ 65.6