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
Jun. 30, 2014
Dec. 31, 2013
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross $ 13,710.0 $ 13,570.9
Allowance for depreciation and depletion (2,705.2) (2,417.5)
Property, plant and equipment, net 11,004.8 11,153.4
Land Rights And Mineral Rights [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 7,854.2 7,819.6
Office And Information Technology [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 125.8 125.7
Buildings [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 307.1 255.2
Mining Equipment [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 2,199.3 1,819.3
Processing Equipment [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 1,943.9 2,148.6
Electric Power Facilities [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 114.6 114.3
Port Facilities [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 105.1 99.4
Interest Capitalized During Construction [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 23.1 23.8
Land Improvements [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 54.5 69.3
Other [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 89.6 104.4
Construction in Progress [Member]
    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross $ 892.8 $ 991.3