Annual report pursuant to Section 13 and 15(d)

Business Summary And Significant Accounting Policies (Depreciation Methods And Useful Lives) (Details)

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Business Summary And Significant Accounting Policies (Depreciation Methods And Useful Lives) (Details)
12 Months Ended
Dec. 31, 2011
U.S. Iron Ore And Eastern Canadian Iron Ore [Member] | Building [Member]
 
Basis Straight line
Life (Years) 45
U.S. Iron Ore And Eastern Canadian Iron Ore [Member] | Equipment [Member]
 
Basis Straight line/Double declining balance
Life, minimum (Years) 10
Life, maximum (Years) 20
U.S. Iron Ore And Eastern Canadian Iron Ore [Member] | Other Machinery And Equipment [Member]
 
Basis Straight line
Life, minimum (Years) 15
Life, maximum (Years) 45
U.S. Iron Ore And Eastern Canadian Iron Ore [Member] | Computer Equipment [Member]
 
Basis Straight line
Life, minimum (Years) 2
Life, maximum (Years) 7
North American Coal [Member] | Building [Member]
 
Basis Straight line
Life (Years) 30
North American Coal [Member] | Equipment [Member]
 
Basis Straight line
Life, minimum (Years) 2
Life, maximum (Years) 22
North American Coal [Member] | Other Machinery And Equipment [Member]
 
Basis Straight line
Life, minimum (Years) 2
Life, maximum (Years) 30
North American Coal [Member] | Computer Equipment [Member]
 
Basis Straight line
Life, minimum (Years) 2
Life, maximum (Years) 3
Asia Pacific Iron Ore [Member] | Property Plant And Equipment [Member]
 
Basis Straight line
Life, minimum (Years) 5
Life, maximum (Years) 10
Asia Pacific Iron Ore [Member] | Mine Development [Member]
 
Basis Production output
Life (Years) 10
Asia Pacific Iron Ore [Member] | Vehicles And Office Equipment [Member]
 
Basis Straight line
Life, minimum (Years) 3
Life, maximum (Years) 5