Long-Term Debt (Schedule Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified			12 Months Ended			0 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, 2012	Dec. 31, 2011	Dec. 31, 2012 6 5/8% Senior Notes Due 2016	Dec. 31, 2011 6 5/8% Senior Notes Due 2016	Jan. 13, 2006 6 5/8% Senior Notes Due 2016	Jul. 17, 2012 Three Point Six Zero Percentage Senior Notes Due Twenty Twenty Two [Member]	Dec. 31, 2012 Three Point Six Zero Percentage Senior Notes Due Twenty Twenty Two [Member]	Dec. 31, 2011 Three Point Six Zero Percentage Senior Notes Due Twenty Twenty Two [Member]	Dec. 31, 2012 GO Zone 6 1/2% Senior Notes Due 2029 [Member]	Dec. 31, 2011 GO Zone 6 1/2% Senior Notes Due 2029 [Member]	Dec. 31, 2012 GO Zone 6 3/4% Senior Notes Due 2032 [Member]	Dec. 31, 2011 GO Zone 6 3/4% Senior Notes Due 2032 [Member]	Dec. 31, 2012 GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]	Dec. 31, 2011 GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]	Dec. 31, 2012 IKE 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, 1997 Waste Disposal Revenue Bonds Due 2027 [Member]	Dec. 31, 2012 Waste Disposal Revenue Bonds Due 2027 [Member]	Dec. 31, 2011 Waste Disposal Revenue Bonds Due 2027 [Member]
Debt Instrument [Line Items]
Senior notes			$ 0	$ 249,674			$ 248,872	$ 0	$ 100,000	$ 100,000	$ 250,000	$ 250,000	$ 89,000	$ 89,000	$ 65,000	$ 65,000
Non-current loan payable																		10,889	10,889
Long-term debt	$ 763,761	$ 764,563
Stated interest rate	6.50%		6.625%	6.625%	6.625%	3.60%	3.60%		6.50%	6.50%	6.75%	6.75%	6.50%	6.50%	6.50%	6.50%
Maturity			2016			2022	2022		2029		2032		2035		2035		December 2027	2027