Derivative Financial Instruments (Fair Value Of Derivative Financial Instruments) (Details) (Not Designated As Hedging Instrument [Member], USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Derivatives, Fair Value [Line Items]
Net derivatives	$ 136,812	$ 88,923
Commodity Contracts [Member] \| Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative financial instruments - Assets	114,034	73,176
Commodity Contracts [Member] \| Long-Term Assets [member]
Derivatives, Fair Value [Line Items]
Derivative financial instruments - Assets	23,356	23,722
Commodity Contracts [Member] \| Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative financial instruments - Liabilities	0	(3,775)
Commodity Contracts [Member] \| Long-Term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative financial instruments - Liabilities	$ (578)	$ (4,200)

Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624163-113959

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-Subparagraph a

-Clause 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 205G

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant