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, 2018
Jan. 01, 2018
Dec. 31, 2017
Inventory, Net [Abstract]      
Total Inventories $ 187.9 $ 87.0 $ 138.4
U.S. Iron Ore [Member]      
Inventory, Net [Abstract]      
Finished Goods 171.8   127.1
Work-in-Process $ 16.1   $ 11.3