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Quarterly report pursuant to Section 13 or 15(d)

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Goodwill) (Details)

v2.4.0.6
GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Goodwill) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2013
Dec. 31, 2012
Goodwill [Roll Forward] Ìý Ìý
Beginning Balance $ 167.4 $ 1,152.1
Arising in business combinations 0 13.8
Impairment 0 (1,000.0)
Impact of foreign currency translation 0.2 1.5
Ending Balance 167.6 167.4
Accumulated Goodwill Impairment Loss (1,027.8) (1,027.8)
U.S. Iron Ore [Member]
 Ìý Ìý
Goodwill [Roll Forward] Ìý Ìý
Beginning Balance 2.0 2.0
Arising in business combinations 0 0
Impairment 0 0
Impact of foreign currency translation 0 0
Ending Balance 2.0 2.0
Accumulated Goodwill Impairment Loss 0 0
Eastern Canadian Iron Ore [Member]
 Ìý Ìý
Goodwill [Roll Forward] Ìý Ìý
Beginning Balance 0 986.2
Arising in business combinations 0 13.8
Impairment 0 (1,000.0)
Impact of foreign currency translation 0 0
Ending Balance 0 0
Accumulated Goodwill Impairment Loss (1,000.0) (1,000.0)
Asia Pacific Iron Ore [Member]
 Ìý Ìý
Goodwill [Roll Forward] Ìý Ìý
Beginning Balance 84.5 83.0
Arising in business combinations 0 0
Impairment 0 0
Impact of foreign currency translation 0.2 1.5
Ending Balance 84.7 84.5
Accumulated Goodwill Impairment Loss 0 0
North American Coal [Member]
 Ìý Ìý
Goodwill [Roll Forward] Ìý Ìý
Beginning Balance 0 0
Arising in business combinations 0 0
Impairment 0 0
Impact of foreign currency translation 0 0
Ending Balance 0 0
Accumulated Goodwill Impairment Loss (27.8) (27.8)
Other Segment [Member]
 Ìý Ìý
Goodwill [Roll Forward] Ìý Ìý
Beginning Balance 80.9 80.9
Arising in business combinations 0 0
Impairment 0 0
Impact of foreign currency translation 0 0
Ending Balance 80.9 80.9
Accumulated Goodwill Impairment Loss $ 0 $ 0