Environmental And Mine Closure Obligations (Summary Of Mine Closure Obligations) (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Environmental	$ 15.0	$ 13.7
Mine closure	210.2	185.4
Total environmental and mine closure obligations	225.2	199.1
Less current portion	14.7	14.2
Long-term environmental and mine closure obligations	210.5	184.9
Mine Closure [Member] \| LTV Steel Mining Company [Member]
Mine closure	17.9	17.1
U.S. Iron Ore [Member] \| Owned Or Operating Facilities [Member]
Mine closure	67.5	62.7
Eastern Canadian Iron Ore [Member] \| Owned Or Operating Facilities [Member]
Mine closure	67.8	49.3
Asia Pacific Iron Ore [Member] \| Owned Or Operating Facilities [Member]
Mine closure	15.2	15.4
North American Coal [Member] \| Owned Or Operating Facilities [Member]
Mine closure	35.6	34.7
Owned Or Operating Facilities [Member] \| Other Regions [Member]
Mine closure	$ 6.2	$ 6.2

Environmental Loss Contingency And Mine Reclamation And Closing Liability Current

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Environmental Loss Contingency And Mine Reclamation And Closing Liability Current And Noncurrent

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Mine Reclamation and Closing Liability

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Total costs accrued as of the balance sheet date for environmental loss contingencies.

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Amount of a reclamation and mine closing liability that is associated with a legal obligation for the closure and reclamation of a mine including the removal of buildings, equipment, machinery and other physical remnants of mining, closure of tailings impoundments, leach pads and other mine features, and contouring, covering and revegetation of waste rock piles and other disturbed areas.

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