Basis of Presentation and Significant Accounting Policies (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Inventories Detail [Table]
Finished goods	$ 64,874,000		$ 64,874,000		$ 72,312,000
Raw materials	4,717,000		4,717,000		5,396,000
Parts and supplies	22,825,000		22,825,000		24,497,000
Work in progress	741,000		741,000		836,000
Inventories	93,157,000		93,157,000		103,041,000
Weighted Average Shares Outstanding [Table]
Number of weighted average common shares outstanding	77,896,000	77,278,000	77,784,000	77,174,000
Assumed exercise of stock options	0	1,720,000	0	1,466,000
Average diluted shares outstanding	77,896,000	78,998,000	77,784,000	78,640,000
Average market price of common stock for the period			$ 9.38
Outstanding stock options excluded from average diluted shares outstanding		3,219,457		2,794,545
Proceeds from insurance settlements			7,600,000
Fair value of Senior Notes	316,900,000		316,900,000		327,400,000
Carrying value of Senior Notes	305,000,000		305,000,000		305,000,000
Fair value of contingent purchase price consideration	$ 2,200,000		$ 2,200,000		$ 2,700,000