GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Goodwill) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Beginning Balance	$ 74.5	$ 167.4
Arising in business combinations	0	0
Impairment	(73.5)	(80.9)
Impact of foreign currency translation	1.0	(12.0)
Ending Balance	2.0	74.5
Accumulated goodwill impairment loss	(1,182.2)	(1,108.7)
U.S. Iron Ore [Member]
Goodwill [Roll Forward]
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]
Goodwill [Roll Forward]
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	(1,000.0)	(1,000.0)
Asia Pacific Iron Ore [Member]
Goodwill [Roll Forward]
Beginning Balance	72.5	84.5
Arising in business combinations	0	0
Impairment	(73.5)	0
Impact of foreign currency translation	1.0	(12.0)
Ending Balance	0	72.5
Accumulated goodwill impairment loss	(73.5)	0
North American Coal [Member]
Goodwill [Roll Forward]
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]
Goodwill [Roll Forward]
Beginning Balance	0	80.9
Arising in business combinations	0	0
Impairment	0	(80.9)
Impact of foreign currency translation	0	0
Ending Balance	0	0
Accumulated goodwill impairment loss	$ (80.9)	$ (80.9)