Acquisitions, Divestitures, and Assets Held for Sale Assets Held for Sale	3 Months Ended
Mar. 31, 2015
Assets held for sale [Abstract]
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 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 over fair value less estimated costs to sell. Subsequent decreases to the estimated fair value less the costs to sell impact the measurement of assets held for sale. As of March 31, 2015, the accompanying balance sheets present $185.0 million of assets held for sale, net of accumulated depletion, depreciation, and amortization expense, which primarily consists of all of the Company’s Mid-Continent region assets. A corresponding asset retirement obligation liability of $14.3 million is separately presented. Earlier in 2015, the Company announced plans to divest of these assets and shift resources to further focus on development of core assets. Write-downs to fair value less estimated costs to sell of $30.0 million for certain of these assets for the three months ended March 31, 2015, are reflected in the gain (loss) on divestiture activity line item in the accompanying condensed consolidated statements of operations (“accompanying statements of operations”). Subsequent to March 31, 2015, the Company entered into purchase and sale agreements with two separate buyers for the sale of its Mid-Continent assets that were classified as held for sale at March 31, 2015. The Company expects to close these transactions in the second quarter of 2015 for a total purchase price of approximately $324 million, subject to customary closing adjustments. The closings of these transactions are subject to the satisfaction of customary closing conditions, and there can be no assurance that either of these transactions will close on the expected closing dates or at all. The Company determined that these planned asset sales do not qualify for discontinued operations accounting under financial statement presentation authoritative guidance. In conjunction with the Company’s efforts to divest its Mid-Continent region assets, the Company announced the planned closure of its Tulsa, Oklahoma office in 2015 with the relocation of certain personnel to other Company offices. The Company anticipates incurring approximately $10 million of exit and disposal costs associated with the severance, retention and relocation of employees, termination of operating leases, vacant office space, and other expenses. The majority of these exit and disposal activities are expected to be completed by the end of the third quarter of 2015. As of March 31, 2015, the Company had recorded $3.5 million of exit and disposal costs, the majority of which were recorded as general and administrative expense within the 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 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 over fair value less estimated costs to sell. Subsequent decreases to the estimated fair value less the costs to sell impact the measurement of assets held for sale.

As of March 31, 2015, the accompanying balance sheets present $185.0 million of assets held for sale, net of accumulated depletion, depreciation, and amortization expense, which primarily consists of all of the Company’s Mid-Continent region assets. A corresponding asset retirement obligation liability of $14.3 million is separately presented. Earlier in 2015, the Company announced plans to divest of these assets and shift resources to further focus on development of core assets. Write-downs to fair value less estimated costs to sell of $30.0 million for certain of these assets for the three months ended March 31, 2015, are reflected in the gain (loss) on divestiture activity line item in the accompanying condensed consolidated statements of operations (“accompanying statements of operations”).

Subsequent to March 31, 2015, the Company entered into purchase and sale agreements with two separate buyers for the sale of its Mid-Continent assets that were classified as held for sale at March 31, 2015. The Company expects to close these transactions in the second quarter of 2015 for a total purchase price of approximately $324 million, subject to customary closing adjustments. The closings of these transactions are subject to the satisfaction of customary closing conditions, and there can be no assurance that either of these transactions will close on the expected closing dates or at all.

The Company determined that these planned asset sales do not qualify for discontinued operations accounting under financial statement presentation authoritative guidance.

In conjunction with the Company’s efforts to divest its Mid-Continent region assets, the Company announced the planned closure of its Tulsa, Oklahoma office in 2015 with the relocation of certain personnel to other Company offices. The Company anticipates incurring approximately $10 million of exit and disposal costs associated with the severance, retention and relocation of employees, termination of operating leases, vacant office space, and other expenses. The majority of these exit and disposal activities are expected to be completed by the end of the third quarter of 2015. As of March 31, 2015, the Company had recorded $3.5 million of exit and disposal costs, the majority of which were recorded as general and administrative expense within the accompanying statements of operations.