Divestitures and Assets Held for Sale	6 Months Ended
Jun. 30, 2012
Divestitures and Assets Held for Sale Disclosure [Abstract]
Divestitures and Assets Held for Sale	Note 3 - Assets Held for Sale Assets are classified as held for sale when the Company commits to a plan to sell the assets and there is reasonable certainty that the sale will take place within one year. Upon classification as held for sale, long-lived assets are no longer depreciated or depleted, and a measurement for impairment is performed to identify and expense any excess of carrying value of the assets held for sale over their fair value less costs to sell. Subsequent changes to the estimated fair value less the costs to sell will impact the measurement of assets held for sale for which fair value less costs to sell is determined to be less than the carrying value of the assets. As of June 30, 2012, the accompanying condensed consolidated balance sheets (“accompanying balance sheets”) present $60.7 million of assets held for sale, net of accumulated depletion, depreciation, and amortization expense. A corresponding asset retirement obligation liability of $1.7 million is separately presented. These assets held for sale include certain assets located in the Company’s Rocky Mountain region, as well as the Company’s Marcellus shale assets in Pennsylvania. The Company determined that these planned asset sales do not qualify for discontinued operations accounting under financial statement presentation authoritative guidance. During the second quarter of 2012, the Company reclassified a portion of the assets previously held for sale as of March 31, 2012, to assets held and used, as these assets were no longer being actively marketed. The assets were measured at the lower of the carrying value of the assets before being classified as held for sale, adjusted for any depletion, depreciation, and amortization expense (“DD&A”) that would have been recognized had the assets been continuously held and used, or the fair value of the assets at the date they no longer met the criteria as held for sale. As a result of this measurement, the Company recognized $1.7 million of DD&A expense and a $28.3 million loss on unsuccessful sale of properties, which is included in gain (loss) on divestiture activity in the accompanying condensed consolidated statements of operations (“accompanying statements of operations”).

Note 3 - Assets Held for Sale

Assets are classified as held for sale when the Company commits to a plan to sell the assets and there is reasonable certainty that the sale will take place within one year. Upon classification as held for sale, long-lived assets are no longer depreciated or depleted, and a measurement for impairment is performed to identify and expense any excess of carrying value of the assets held for sale over their fair value less costs to sell. Subsequent changes to the estimated fair value less the costs to sell will impact the measurement of assets held for sale for which fair value less costs to sell is determined to be less than the carrying value of the assets.

As of June 30, 2012, the accompanying condensed consolidated balance sheets (“accompanying balance sheets”) present $60.7 million of assets held for sale, net of accumulated depletion, depreciation, and amortization expense. A corresponding asset retirement obligation liability of $1.7 million is separately presented. These assets held for sale include certain assets located in the Company’s Rocky Mountain region, as well as the Company’s Marcellus shale assets in Pennsylvania. The Company determined that these planned asset sales do not qualify for discontinued operations accounting under financial statement presentation authoritative guidance.

During the second quarter of 2012, the Company reclassified a portion of the assets previously held for sale as of March 31, 2012, to assets held and used, as these assets were no longer being actively marketed. The assets were measured at the lower of the carrying value of the assets before being classified as held for sale, adjusted for any depletion, depreciation, and amortization expense (“DD&A”) that would have been recognized had the assets been continuously held and used, or the fair value of the assets at the date they no longer met the criteria as held for sale. As a result of this measurement, the Company recognized $1.7 million of DD&A expense and a $28.3 million loss on unsuccessful sale of properties, which is included in gain (loss) on divestiture activity in the accompanying condensed consolidated statements of operations (“accompanying statements of operations”).