GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Goodwill) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Goodwill [Roll Forward]
Beginning Balance	$ 167.4	$ 1,152.1
Arising in business combinations	0	13.8
Impairment	(80.9)	(1,000.0)
Impact of foreign currency translation	(12.0)	1.5
Ending Balance	74.5	167.4
Accumulated Goodwill Impairment Loss	(1,108.7)	(1,027.8)
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	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]
Goodwill [Roll Forward]
Beginning Balance	84.5	83.0
Arising in business combinations	0	0
Impairment	0	0
Impact of foreign currency translation	(12.0)	1.5
Ending Balance	72.5	84.5
Accumulated Goodwill Impairment Loss	0	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	80.9	80.9
Arising in business combinations	0	0
Impairment		0
Impact of foreign currency translation	0	0
Ending Balance	0	80.9
Accumulated Goodwill Impairment Loss	$ (80.9)	$ 0