Quarterly report pursuant to Section 13 or 15(d)

Segment Reporting (Narrative) (Detail)

v2.4.0.6
Segment Reporting (Narrative) (Detail)
6 Months Ended
Jun. 30, 2012
Facility
Sonoma [Member]
 
Segment Reporting Information [Line Items]  
Ownership interest, percent 45.00%
U.S. Iron Ore [Member]
 
Segment Reporting Information [Line Items]  
Number of mines 5
Eastern Canadian Iron Ore [Member]
 
Segment Reporting Information [Line Items]  
Number of mines 2
Asia Pacific Coal [Member] | Sonoma [Member]
 
Segment Reporting Information [Line Items]  
Ownership interest, percent 45.00%
Latin American Iron Ore [Member] | Amapa [Member]
 
Segment Reporting Information [Line Items]  
Percent ownership interest 30.00%
Metallurgical Coal Mines [Member] | North American Coal [Member]
 
Segment Reporting Information [Line Items]  
Number of mines 5
Thermal Coal Mines [Member] | North American Coal [Member]
 
Segment Reporting Information [Line Items]  
Number of mines 1