Quarterly report pursuant to Section 13 or 15(d)

PROPERTY, PLANT AND EQUIPMENT (Value Of Each Of The Major Classes Of Consolidated Depreciable Assets) (Details)

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PROPERTY, PLANT AND EQUIPMENT (Value Of Each Of The Major Classes Of Consolidated Depreciable Assets) (Details) (USD $)
In Millions, unless otherwise specified
Sep. 30, 2013
Dec. 31, 2012
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross $ 13,525.8 $ 13,044.7
Allowance for depreciation and depletion (2,171.0) (1,837.4)
Property, plant and equipment, net 11,354.8 11,207.3
Land Rights And Mineral Rights [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 7,826.5 7,920.8
Office And Information Technology [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 119.3 92.4
Buildings [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 214.0 162.0
Mining Equipment [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 1,554.7 1,290.7
Processing Equipment [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 2,172.8 1,937.4
Railroad Equipment [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 222.3 240.8
Electric Power Facilities [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 82.9 58.7
Port Facilities [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 103.8 114.3
Capitalized Interest Charges [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 25.5 20.8
Land Improvements [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 63.0 43.9
Other [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 91.8 39.0
Construction in Progress [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross $ 1,049.2 $ 1,123.9