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