Annual report pursuant to Section 13 and 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
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross $ 13,570.9 $ 13,044.7  
Allowance for depreciation and depletion (2,417.5) (1,837.4)  
Property, plant and equipment, net 11,153.4 11,207.3 10,404.1
Land Rights And Mineral Rights [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 7,819.6 7,920.8  
Office And Information Technology [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 125.7 92.4  
Buildings [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 255.2 162.0  
Mining Equipment [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 1,600.3 1,290.7  
Processing Equipment [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 2,148.6 1,937.4  
Railroad Equipment [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 219.0 240.8  
Electric Power Facilities [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 114.3 58.7  
Port Facilities [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 99.4 114.3  
Capitalized Interest Charges [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 23.8 20.8  
Land Improvements [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 69.3 43.9  
Other [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross 104.4 39.0  
Construction in Progress [Member]
      
Property, Plant and Equipment [Line Items]      
Property, plant and equipment, gross $ 991.3 $ 1,123.9