Fair Value Measurements (Schedule Of Carrying And Fair Values Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended	1 Months Ended	12 Months Ended			12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2011	Jan. 31, 2006 6 5/8% Senior Notes Due 2016 [Member]	Dec. 31, 2011 6 5/8% Senior Notes Due 2016 [Member]	Dec. 31, 2010 6 5/8% Senior Notes Due 2016 [Member]	Jan. 13, 2006 6 5/8% Senior Notes Due 2016 [Member]	Dec. 31, 2011 GO Zone 6 1/2% Senior Notes Due 2029 [Member]	Dec. 31, 2010 GO Zone 6 1/2% Senior Notes Due 2029 [Member]	Dec. 31, 2011 GO Zone 6 3/4% Senior Notes Due 2032 [Member]	Dec. 31, 2010 GO Zone 6 3/4% Senior Notes Due 2032 [Member]	Dec. 31, 2011 GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]	Dec. 31, 2010 GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]	Dec. 31, 2011 IKE Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]	Dec. 31, 2010 IKE Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]	Dec. 31, 1997 Waste Disposal Revenue Bonds Due 2027 [Member]	Dec. 31, 2011 Waste Disposal Revenue Bonds Due 2027 [Member]	Dec. 31, 2010 Waste Disposal Revenue Bonds Due 2027 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Carrying Value			$ 249,674	$ 249,593		$ 100,000	$ 100,000	$ 250,000	$ 250,000	$ 89,000	$ 89,000	$ 65,000	$ 65,000
Senior Notes, Fair Value			254,890	258,438		108,834	99,875	263,988	251,925	93,090	88,653	67,987	64,905
Loans, Carrying Value															10,889	10,889
Loans, Fair Value															$ 10,889	$ 10,889
Stated interest rate			6.625%	6.625%	6.625%	6.50%	6.50%	6.75%	6.75%	6.50%	6.50%	6.50%	6.50%
Maturity date	2016	2016	2016			2029		2032		2035		2035		December 2027	2027