Fair Value Measurements (Schedule Of Carrying And Fair Values Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified		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, 2013	Jul. 17, 2012 3.60% Senior Notes Due 2022 [Member]	Dec. 31, 2013 3.60% Senior Notes Due 2022 [Member]	Dec. 31, 2012 3.60% Senior Notes Due 2022 [Member]	Sep. 30, 2012 3.60% Senior Notes Due 2022 [Member]	Dec. 31, 2013 GO Zone 6 1/2% Senior Notes Due 2029 [Member]	Dec. 31, 2012 GO Zone 6 1/2% Senior Notes Due 2029 [Member]	Dec. 31, 2013 GO Zone 6 3/4% Senior Notes Due 2032 [Member]	Dec. 31, 2012 GO Zone 6 3/4% Senior Notes Due 2032 [Member]	Dec. 31, 2013 GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]	Dec. 31, 2012 GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]	Dec. 31, 2013 Ike Zone Six Point Five Percent Tax Exempt Revenue Bonds Due Twenty Thirty Five [Member]	Dec. 31, 2012 Ike Zone Six Point Five Percent Tax Exempt Revenue Bonds Due Twenty Thirty Five [Member]	Dec. 31, 1997 Waste Disposal Revenue Bonds Due 2027 [Member]	Dec. 31, 2013 Waste Disposal Revenue Bonds Due 2027 [Member]	Dec. 31, 2012 Waste Disposal Revenue Bonds Due 2027 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Carrying Value			$ 248,990	$ 248,872		$ 100,000	$ 100,000	$ 250,000	$ 250,000	$ 89,000	$ 89,000	$ 65,000	$ 65,000
Senior Notes, Fair Value			236,905	251,125		109,490	119,738	265,148	283,168	94,606	102,095	69,094	74,564
Loans, Carrying Value															10,889	10,889
Loans, Fair Value															$ 10,889	$ 10,889
Stated interest rate	6.50%	3.60%	3.60%	3.60%	3.60%	6.50%	6.50%	6.75%	6.75%	6.50%	6.50%	6.50%	6.50%
Maturity date		2022	2022			2029		2032		2035		2035		December 2027	2027