Quarterly report pursuant to Section 13 or 15(d)

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Narrative) (Details)

v2.4.0.8
ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
 6 Months Ended
Jun. 30, 2013
Dec. 31, 2012
Jun. 30, 2013
LTV Steel Mining Company [Member]
Facility
Jun. 30, 2013
U.S. Iron Ore [Member]
Facility
Jun. 30, 2013
Eastern Canadian Iron Ore [Member]
Facility
Jun. 30, 2013
Asia Pacific Iron Ore [Member]
Facility
Jun. 30, 2013
North American Coal [Member]
Facility
Loss Contingencies [Line Items]              
Total environmental and mine closure obligations $ 248.0 $ 265.1          
Mine closure obligation, number of mines (in number of facilities)     1 4 2 1 5