Fair Value of Derivative and Balance Sheet Location (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Derivatives, Fair Value
Derivative Asset, Fair Value, Net	$ (7,508)		$ (11,437)
Derivative Asset, Fair Value, Gross Asset	26,708		58,925
Derivative Liability, Fair Value, Net	(7,508)		(11,437)
Derivative Liability, Fair Value, Gross Liability	10,177		28,576
Current Assets
Derivatives, Fair Value
Derivative Asset, Fair Value, Net	16,287		52,042
Non Current Assets
Derivatives, Fair Value
Derivative Asset, Fair Value, Net	10,421		6,883
Current Liabilities
Derivatives, Fair Value
Derivative Liability, Fair Value, Net	5,702		18,439
Non Current Liabilities
Derivatives, Fair Value
Derivative Liability, Fair Value, Net	4,475		10,137
Commodity Contracts Related to Natural Gas and Crude Oil Sales | Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	15,099		47,016
Commodity Contracts Related to Natural Gas and Crude Oil Sales | Non Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	10,197		6,671
Commodity Contracts Related to Natural Gas and Crude Oil Sales | Current Liabilities
Derivatives, Fair Value
Fair Value of Derivatives	2,968		1,744
Commodity Contracts Related to Natural Gas and Crude Oil Sales | Non Current Liabilities
Derivatives, Fair Value
Fair Value of Derivatives	4,437		9,969
Commodity Contracts Related to Affiliated Partnership | Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	0	[1],[2]	4,707	[1],[2]
Commodity Contracts Related to Natural Gas Marketing | Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	661		302
Commodity Contracts Related to Natural Gas Marketing | Non Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	92		203
Commodity Contracts Related to Natural Gas Marketing | Current Liabilities
Derivatives, Fair Value
Fair Value of Derivatives	507		226
Commodity Contracts Related to Natural Gas Marketing | Non Current Liabilities
Derivatives, Fair Value
Fair Value of Derivatives	36		168
Basis Protection Contracts Related to Natural Gas Marketing | Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	21		17
Basis Protection Contracts Related to Natural Gas Marketing | Non Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	3		9
Basis Protection Contracts Related to Natural Gas Marketing | Current Liabilities
Derivatives, Fair Value
Fair Value of Derivatives	3		0
Basis Protection Contracts Related to Natural Gas Marketing | Non Current Liabilities
Derivatives, Fair Value
Fair Value of Derivatives	2		0
Basis Protection Contracts Related to Affiliated Partnerships | Current Liabilities
Derivatives, Fair Value
Fair Value of Derivatives	0	[1],[3]	2,140	[1],[3]
Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	506		0
Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Non Current Assets
Derivatives, Fair Value
Fair Value of Derivatives	129		0
Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Current Liabilities
Derivatives, Fair Value
Fair Value of Derivatives	$ 2,224		$ 14,329

[1] In June 2013, all remaining derivative positions designated to our affiliated partnerships were liquidated prior to settlement. The net proceeds are included in the balance sheet line item accounts payable affiliates.

[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.