| **Asset Retirement Obligations (Tables)**                            | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
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| **Asset Retirement Obligation [Abstract]**                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Schedule of Change in Asset Retirement Obligation [Table Text Block] | The following table presents the changes in carrying amounts of the asset retirement obligations associated with our working interest in natural gas and crude oil properties:  Amount (in thousands)  Balance at December 31, 2011$46,566Obligations incurred with development activities and assumed with acquisitions14,066Accretion expense2,839Obligations discharged with disposal of properties and asset retirements(2,196)Balance at September 30, 201261,275Less current portion(1,000)Long-term portion$60,275   |

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| - Details**Name:**us-gaap_AssetRetirementObligationAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
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| - Definition
Tabular disclosure of the changes in carrying amount of a liability for asset retirement obligations, for changes such as new obligations, changes in estimates of existing obligations, spending on existing obligations, property dispositions, and foreign currency translation.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13201-110859
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