|**Asset Retirement Obligations**                      | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
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|**Asset Retirement Obligation Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Asset Retirement Obligation Disclosure                | ASSET RETIREMENT OBLIGATIONSThe following table presents the changes in carrying amounts of the asset retirement obligations associated with our working interest in crude oil and natural gas properties:Amount(in thousands)Balance at beginning of period, January 1, 2015$73,855Obligations incurred with development activities302Accretion expense1,560Obligations discharged with asset retirements(777)Balance end of period, March 31, 201574,940Less current portion(2,792)Long-term portion$72,148Short-term asset retirement obligations are included in other accrued expenses on the condensed consolidated balance sheets.
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|                                                      | Amount                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|                                                      | (in thousands)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Balance at beginning of period, January 1, 2015       | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|Obligations incurred with development activities      | 302                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Accretion expense                                     | 1,560                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Obligations discharged with asset retirements         | (777                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Balance end of period, March 31, 2015                 | 74,940                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Less current portion                                  | (2,792                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Long-term portion                                     | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
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                    duration X- DefinitionThe entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7569-110849+ Details**Name:**
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