Contingencies (Details) (USD $)	1 Months Ended		3 Months Ended		12 Months Ended			0 Months Ended		12 Months Ended					12 Months Ended		12 Months Ended	1 Months Ended	12 Months Ended				0 Months Ended	12 Months Ended
	Nov. 30, 2009	Dec. 31, 2008	Jun. 30, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Mar. 02, 2007 Minimum [Member]	Mar. 02, 2007 Maximum [Member]	Dec. 31, 2011 Antidumping Tariffs After October 11, 2006 Through March 1, 2007 [Member]	Dec. 31, 2011 March 2, 2007 Through March 29, 2007 [Member]	Dec. 31, 2011 March 30, 2007 Through April 8, 2007 [Member]	Dec. 31, 2011 April 19, 2007 Through November 9, 2009 [Member]	Dec. 31, 2011 April 1, 2009 Through March 31, 2010 [Member]	Dec. 31, 2011 April 1, 2010 Through March 31, 2011 [Member]	Dec. 31, 2011 October 11, 2006 Through March 31, 2008 [Member]	Dec. 31, 2011 October 11, 2006 To September 30, 2007 [Member]	Oct. 25, 2011 August 2011 Through November 2011 [Member]	Dec. 31, 2011 Revised Rate [Member] October 11, 2006 Through March 31, 2008 [Member]	Dec. 31, 2011 In Situ [Member]	Dec. 31, 2011 Ex Situ [Member] Minimum [Member]	Dec. 31, 2011 Ex Situ [Member] Maximum [Member]	Dec. 21, 2010 ADA-ES [Member]	Dec. 31, 2011 ADA-ES [Member]	Dec. 31, 2010 ADA-ES [Member]	Dec. 31, 2009 ADA-ES [Member]	Dec. 31, 2010 FYEO [Member]	Dec. 31, 2009 FYEO [Member]
Contingencies [Line Items]
Minimum purchase obligation																								$ 55,000,000
Minimum purchase obligation contract period																								5 year
Contingency past damages value																								3,000,000
Future damages sought value																								9,000,000
Recognized litigation expense																									6,700,000	250,000	3,300,000	800,000
Litigation settlement amount																							7,200,000				4,300,000
Recorded liability estimates for environmental loss contingencies				3,900,000	2,000,000	3,900,000
Receivable for expected refunds for tariff deposits made														1,100,000		1,600,000
Receivable for anticipated CDSOA distributions																	300,000
Refunds received for tariff deposits made																1,000,000
Reduction in environmental loss contingency			1,300,000		1,300,000
Environmental remediation costs					700,000	100,000	0
Percentage of special additional duties tariff rates for the subject merchandise as determined by the commerce department								61.95%	228.11%
Percentage of final antidumping duty collected																	59.57%
Antidumping duty rate					14.51%					84.45%	78.89%	69.54%	69.54%		14.51%			0.00%	14.51%
Estimated liability for tariffs reflected in accounts payable and accrued liabilities				200,000	100,000	200,000
Rate of adjustment for certain ministerial errors					0.07%
Assessment rate on the entries made in the period					31.93%
New deposit rate established by cooperative respondents involved in POR II					31.59%
Tariff collection value per pound basis					$ 0.127
Potential proceeds from refunds of tariff deposits					1,100,000
Tariff collection value per pound basis in POR III					$ 0.127
Number of factors involved in contingent liability relating to tariffs paid on imports					2
Additional amount on distribution of tariffs collected					0	0
Distributions received under Continued Dumping and Subsidy Offset Act	800,000	200,000
Distributions received as a percentage of total amount available					59.57%
Accrued potential loss related to civil penalties				2,000,000
Capital costs expected to be accrued related to civil penalties					10,000,000
Minimum estimated cost of remedial program for Operable Unit #1 at the site					11,000,000
Maximum estimated cost of remedial program for Operable Unit #1 at the site					14,000,000
Estimated costs for thermal treatment of soils																				$ 11,000,000	$ 5,500,000	$ 8,500,000