|**Fair Value of Derivative and Balance Sheet Location (Details) (USD $)In Thousands, unless otherwise specified**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | Sep. 30, 2013                                                                                                                                                                                                                                                                                             | Dec. 31, 2012                                                                                                                                                                                                                                                                                   
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Derivative Asset, Fair Value, Gross Asset                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | $ 15,582                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                 
|Derivative Liability, Fair Value, Gross Liability                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 21,196                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                 
|Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Derivative Asset, Fair Value, Gross Asset                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 9,660                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                 
|Non Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Derivative Asset, Fair Value, Gross Asset                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 5,922                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                 
|Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Derivative Liability, Fair Value, Gross Liability                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 14,623                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                 
|Non Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Derivative Liability, Fair Value, Gross Liability                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 6,573                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                 
|Commodity Contracts Related to Natural Gas and Crude Oil Sales | Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 9,067                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                 
|Commodity Contracts Related to Natural Gas and Crude Oil Sales | Non Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 5,792                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                 
|Commodity Contracts Related to Natural Gas and Crude Oil Sales | Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 12,880                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                 
|Commodity Contracts Related to Natural Gas and Crude Oil Sales | Non Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 6,403                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                 
|Commodity Contracts Related to Affiliated Partnership | Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 0                                                                                                                                                                                                                                                                                                         | [1]                                                                                                                                                                                                                                                                                             
|Commodity Contracts Related to Natural Gas Marketing | Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 444                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                 
|Commodity Contracts Related to Natural Gas Marketing | Non Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 85                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                 
|Commodity Contracts Related to Natural Gas Marketing | Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 310                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                 
|Commodity Contracts Related to Natural Gas Marketing | Non Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 40                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                 
|Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 133                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                 
|Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Non Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 44                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                 
|Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 1,433                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                 
|Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Non Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 130                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                 
|Basis Protection Contracts Related to Natural Gas Marketing | Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 16                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                 
|Basis Protection Contracts Related to Natural Gas Marketing | Non Current Assets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 1                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                 
|Basis Protection Contracts Related to Affiliated Partnerships | Current Liabilities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|**Derivatives, Fair Value**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                 
|Fair Value of Derivatives                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | $ 0                                                                                                                                                                                                                                                                                                       | [2]                                                                                                                                                                                                                                                                                             
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|[1]
              Represents derivative positions designated to our affiliated partnerships. Accordingly, our accompanying December 31, 2012 condensed consolidated balance sheet includes a corresponding payable to our affiliated partnerships representing their proportionate share of the derivative assets.[2]
              Represents derivative positions designated to our affiliated partnerships. Accordingly, our accompanying December 31, 2012 condensed consolidated balance sheet includes a corresponding receivable from our affiliated partnerships representing their proportionate share of the derivative liabilities | [1]                                                                                                                                                                                                                                                                                                       | Represents derivative positions designated to our affiliated partnerships. Accordingly, our accompanying December 31, 2012 condensed consolidated balance sheet includes a corresponding payable to our affiliated partnerships representing their proportionate share of the derivative assets.
|[1]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | Represents derivative positions designated to our affiliated partnerships. Accordingly, our accompanying December 31, 2012 condensed consolidated balance sheet includes a corresponding payable to our affiliated partnerships representing their proportionate share of the derivative assets.         
|[2]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | Represents derivative positions designated to our affiliated partnerships. Accordingly, our accompanying December 31, 2012 condensed consolidated balance sheet includes a corresponding receivable from our affiliated partnerships representing their proportionate share of the derivative liabilities

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