Organization and Basis of Presentation - Derivative Gains and Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instruments, net	$ 34,036	$ (53,391)
Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Open non-cash mark-to-market losses on derivative instruments	(59,651)	(33,681)
Closed gains (losses) on derivative instruments	93,687	(19,710)
Gain (loss) on derivative instruments, net	$ 34,036	$ (53,391)

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

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- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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