Quarterly report pursuant to Section 13 or 15(d)

Inventories (Schedule Of Inventories) (Detail)

v2.4.0.6
Inventories (Schedule Of Inventories) (Detail) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Inventories [Line Items]    
Finished Goods $ 504.8 $ 291.3
Work-in Process 236.2 184.4
Total Inventory 741.0 475.7
U.S. Iron Ore [Member]
   
Inventories [Line Items]    
Finished Goods 290.8 100.2
Work-in Process 36.8 8.5
Total Inventory 327.6 108.7
Eastern Canadian Iron Ore [Member]
   
Inventories [Line Items]    
Finished Goods 103.6 96.2
Work-in Process 50.8 43.0
Total Inventory 154.4 139.2
North American Coal [Member]
   
Inventories [Line Items]    
Finished Goods 61.7 19.7
Work-in Process 90.2 110.5
Total Inventory 151.9 130.2
Asia Pacific Iron Ore [Member]
   
Inventories [Line Items]    
Finished Goods 27.2 57.2
Work-in Process 57.2 21.6
Total Inventory 84.4 78.8
Other Segment [Member]
   
Inventories [Line Items]    
Finished Goods 21.5 18.0
Work-in Process 1.2 0.8
Total Inventory $ 22.7 $ 18.8