Fair Value of Derivatives and Balance Sheet Location (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Net	$ 31,730	[1]	$ 49,080	[1]
Derivative Asset, Fair Value, Net	107,137	[1]	101,984	[1]
Derivative Instruments in Hedges, at Fair Value, Net	0		0
Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Net	71,217	[1]	60,809	[1]
Non Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Net	35,920	[1]	41,175	[1]
Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Net	18,155	[1]	27,974	[1]
Non Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Net	13,575	[1]	21,106	[1]
Commodity Contracts Related to Natural Gas and Crude Oil Sales [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	62,626	[1]	51,220	[1]
Commodity Contracts Related to Natural Gas and Crude Oil Sales [Member] | Non Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	32,405	[1]	34,938	[1]
Commodity Contracts Related to Natural Gas and Crude Oil Sales [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	(984)	[1]	7,498	[1]
Commodity Contracts Related to Natural Gas and Crude Oil Sales [Member] | Non Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	5,021	[1]	4,357	[1]
Commodity Contracts Related to Affiliated Partnership [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	7,770	[1],[2]	8,018	[1],[2]
Commodity Contracts Related to Affiliated Partnership [Member] | Non Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	3,284	[1],[2]	6,134	[1],[2]
Commodity Contracts Related to Affiliated Partnership [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	211	[1],[3]	211	[1],[3]
Commodity Contracts Related to Affiliated Partnership [Member] | Non Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	73	[1],[3]	113	[1],[3]
Commodity Contracts Related to Natural Gas Marketing [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	792	[1]	1,528	[1]
Commodity Contracts Related to Natural Gas Marketing [Member] | Non Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	214	[1]	103	[1]
Commodity Contracts Related to Natural Gas Marketing [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	732	[1]	1,384	[1]
Commodity Contracts Related to Natural Gas Marketing [Member] | Non Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	170	[1]	93	[1]
Basis Protection Contracts Related to Natural Gas Marketing [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	29	[1]	43	[1]
Basis Protection Contracts Related to Natural Gas Marketing [Member] | Non Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	17	[1]	0	[1]
Basis Protection Contracts Related to Natural Gas Marketing [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	2	[1]	3	[1]
Basis Protection Contracts Related to Natural Gas and Crude Oil Sales [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	15,202	[1]	15,762	[1]
Basis Protection Contracts Related to Natural Gas and Crude Oil Sales [Member] | Non Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	6,947	[1]	13,820	[1]
Basis Protection Contracts Related to Affiliated Partnerships [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	2,992	[1],[3]	3,116	[1],[3]
Basis Protection Contracts Related to Affiliated Partnerships [Member] | Non Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivatives	$ 1,364	[1],[3]	$ 2,723	[1],[3]

[1] As of June 30, 2012 and December 31, 2011, none of our derivative instruments were designated as hedges.

[2] Represents derivative positions designated to our affiliated partnerships; accordingly, our accompanying balance sheets include a corresponding payable to our affiliated partnerships representing their proportionate share of the derivative assets.

[3] Represents derivative positions designated to our affiliated partnerships; accordingly, our accompanying balance sheets include a corresponding receivable from our affiliated partnerships representing their proportionate share of the derivative liabilities.