Fair Value (Schedule Of Carrying Amounts And Fair Values Of Financial Assets/Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| NYMEX Commodity Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset	$ 78,443	$ 96,142
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	(3,420,351)	(3,212,462)
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Interest Rate Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	(508)	(26,478)
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivables	21,681	30,200
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivables	21,681	30,200
Debt	(3,420,351)	(3,212,462)
Estimate of Fair Value Measurement [Member] \| NYMEX Commodity Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset	78,443	96,142
Estimate of Fair Value Measurement [Member] \| Interest Rate Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	(508)	(26,478)
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivables	22,055	28,611
Debt	(3,407,114)	(2,982,895)
Reported Value Measurement [Member] \| NYMEX Commodity Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset	78,443	96,142
Reported Value Measurement [Member] \| Interest Rate Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	$ (508)	$ (26,478)

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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-Publisher FASB

-Name Accounting Standards Codification

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

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- Definition

Fair value portion of receivables, including, but not limited to, trade account receivables, note receivables, and loan receivables.

+ References

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-Publisher FASB

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3, 4

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