Contractual interest rate for funds borrowed, under the debt agreement.

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Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

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Long-Term Debt (Schedule Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended	12 Months Ended	1 Months Ended
	Jul. 17, 2012	Dec. 31, 2014	Dec. 31, 1997	Dec. 31, 2013	Sep. 30, 2012
Debt Instrument [Line Items]
Long-term debt		$ 763,997us-gaap_LongTermDebtNoncurrent		$ 763,879us-gaap_LongTermDebtNoncurrent
Stated interest rate		6.50%
3.60% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Senior notes		249,108		248,990
Stated interest rate	3.60%	3.60%		3.60%	3.60%
Maturity	2022	2022
GO Zone 6 1/2% Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Senior notes		100,000		100,000
Stated interest rate		6.50%		6.50%
Maturity		2029
GO Zone 6 3/4% Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Senior notes		250,000		250,000
Stated interest rate		6.75%		6.75%
Maturity		2032
GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]
Debt Instrument [Line Items]
Senior notes		89,000		89,000
Stated interest rate		6.50%		6.50%
Maturity		2035
Ike Zone Six Point Five Percent Tax Exempt Revenue Bonds Due Twenty Thirty Five [Member]
Debt Instrument [Line Items]
Senior notes		65,000		65,000
Stated interest rate		6.50%		6.50%
Maturity		2035
Waste Disposal Revenue Bonds Due 2027 [Member]
Debt Instrument [Line Items]
Non-current loan payable		$ 10,889		$ 10,889
Maturity		2027	December 2027