Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) (USD $)					12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2011 Land Improvements [Member] years	Dec. 31, 2011 Building Improvements [Member] years	Dec. 31, 2011 Machinery And Equipment [Member] years	Dec. 31, 2011 Major Plant Components Of Machinery And Equipment [Member] years	Dec. 31, 2011 Property, Plant And Equipment Under Capital Lease [Member] years	Dec. 31, 2011 Long Term Mineral Rights And Production Equipment Costs [Member] years	Dec. 31, 2011 Short-Lived Equipment [Member] years	Dec. 31, 2011 Production Process Equipment [Member] years	Dec. 31, 2011 Production Process Equipment (Major Unit Components) [Member] years	Dec. 31, 2011 Production Process Equipment (Infrastructure And Other) [Member] years	Dec. 31, 2011 Assets Held Under Capital Leases [Member] years
Property, Plant and Equipment [Line Items]
Land	$ 59,137,000		$ 55,638,000
Land improvements	50,302,000		48,798,000
Buildings and improvements	186,444,000		204,858,000
Machinery and equipment	1,552,557,000	[1]	1,484,515,000	[1]
Machinery and equipment (major plant components)	541,953,000	[2]	502,906,000	[2]
Property, plant and equipment under capital lease	24,652,000	[3]	24,652,000	[3]
Long-term mineral rights and production equipment costs	62,245,000		60,630,000
Construction in progress	142,138,000		58,181,000
Total	2,619,428,000		2,440,178,000
Property, plant and equipment, Useful Lives, minimum, years					5	10	3	20	19	7	3	8	20	30	19
Property, plant and equipment, Useful Lives, maximum, years					30	45	19	45	50	60	7	19	29	45	25
Buildings, cost of															$ 1,300,000
Useful life of buildings															50

[1] Consists primarily of (1) short-lived production equipment components, office and building equipment and other equipment with estimated lives ranging 3 - 7 years, and (2) production process equipment (intermediate components) with estimated lives ranging 8 - 19 years.

[2] Consists primarily of (1) production process equipment (major unit components) with estimated lives ranging 20 - 29 years, and (2) production process equipment (infrastructure and other) with estimated lives ranging 30 - 45 years.

[3] Assets under capital lease are primarily machinery and equipment with useful lives ranging from 19 - 25 years. Includes a building with a cost of $1.3 million which has a useful life of 50 years.