| **Fair Value of Derivative and Balance Sheet Location (Details) (USD $)In Thousands, unless otherwise specified** | Mar. 31, 2014 | Dec. 31, 2013 |
|-------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Derivatives, Fair Value**                                                                                       |          |          |
| Derivative Asset, Fair Value, Gross Asset                                                                         | $ 3,393       | $ 8,173       |
| Derivative Liability, Fair Value, Gross Liability                                                                 | 32,681        | 18,530        |
| Current Assets                                                                                                    |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Derivative Asset, Fair Value, Gross Asset                                                                         | 827           | 2,572         |
| Non Current Assets                                                                                                |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Derivative Asset, Fair Value, Gross Asset                                                                         | 2,566         | 5,601         |
| Current Liabilities                                                                                               |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Derivative Liability, Fair Value, Gross Liability                                                                 | 29,214        | 15,515        |
| Non Current Liabilities                                                                                           |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Derivative Liability, Fair Value, Gross Liability                                                                 | 3,467         | 3,015         |
| Commodity Contracts Related to Natural Gas and Crude Oil Sales | Current Assets                                   |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 552           | 2,016         |
| Commodity Contracts Related to Natural Gas and Crude Oil Sales | Non Current Assets                               |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 2,214         | 5,055         |
| Commodity Contracts Related to Natural Gas and Crude Oil Sales | Current Liabilities                              |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 28,921        | 15,263        |
| Commodity Contracts Related to Natural Gas and Crude Oil Sales | Non Current Liabilities                          |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 3,302         | 2,782         |
| Commodity Contracts Related to Natural Gas Marketing | Current Assets                                             |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 275           | 361           |
| Commodity Contracts Related to Natural Gas Marketing | Non Current Assets                                         |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 202           | 278           |
| Commodity Contracts Related to Natural Gas Marketing | Current Liabilities                                        |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 171           | 247           |
| Commodity Contracts Related to Natural Gas Marketing | Non Current Liabilities                                    |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 165           | 233           |
| Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Current Assets                            |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 0             | 195           |
| Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Non Current Assets                        |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 150           | 268           |
| Basis Protection Contracts Related to Natural Gas and Crude Oil Sales | Current Liabilities                       |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | 120           | 0             |
| Basis Protection Contracts Related to Natural Gas Marketing [Member] | Current Liabilities                        |          |          |
| **Derivatives, Fair Value**                                                                                       |          |          |
| Fair Value of Derivatives                                                                                         | $ 2           | $ 5           |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226000-175313Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226000-175313Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959
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| X                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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