Subsequent Events (Notes)	3 Months Ended
Sep. 30, 2013
Subsequent Events [Abstract]
Subsequent Events [Text Block]	11. Subsequent Events During the third quarter of 2013, the Company agreed in three separate transactions to sell certain non-core assets, including substantially all of its remaining Barnett Shale assets, certain non-core assets in East Texas, and acreage in non-core areas of the Marcellus Shale, for an aggregate agreed upon sales price of $248.5 million and the assumption of certain liabilities and contractual obligations, subject to customary closing conditions and purchase price adjustments. In one of these transactions, the Company agreed to sell substantially all of its remaining Barnett Shale assets (the "Barnett Transaction") to affiliates of EnerVest Ltd. ("EnerVest") for an agreed upon purchase price of $218.0 million, subject to closing and post-closing purchase price adjustments and the assumption by EnerVest of certain liabilities and contractual obligations. The Barnett Transaction had an effective date of July 1, 2013. The Company closed the sale of its non-core East Texas assets in early September for $8.7 million. The Company closed the Barnett Transaction and the sale of its non-core Marcellus Shale assets in late October and as of October 31, 2013, the Company has received aggregate net proceeds related to these two asset sales totaling approximately $209.7 million. In addition, as a consequence of certain post-closing adjustments and holdbacks, the Company could receive up to an additional $23.8 million in cash proceeds related to such sales. In connection with the Barnett Transaction, the Company entered into derivative instruments on behalf of EnerVest. These derivative instruments were novated to EnerVest upon the closing of the Barnett Transaction. As of September 30, 2013, these derivative instruments were in a net asset position and had a fair market value of $0.5 million. Avista Transaction. Effective September 2011, the Company entered into a joint venture in the Utica Shale with Avista. On October 31, 2013, the Company completed the acquisition of acreage located primarily in Guernsey and Noble counties, Ohio from Avista. The transaction had an effective date of July 1, 2013, and the Company paid Avista $73.2 million in cash, subject to post-closing adjustments. The Company had an ownership in the working interest of the properties acquired through the Avista Utica Shale Joint Venture. The properties in the Avista Utica Joint Venture were held with an equal interest by the Company and Avista. The agreement provides for post-closing price and acreage adjustments and indemnities. In connection with the Avista Transaction, the Company terminated the previously existing Avista Utica Shale Joint Venture agreements. After giving effect to the Avista Transaction, the Company and Avista remain working interest partners in the Utica Shale with the Company acting as the operator of the jointly owned properties which are now subject to standard joint operating agreements. The Company and Avista have established a new area of mutual interest that has been significantly reduced in coverage area and now applies only to certain of those areas in which the Company and Avista jointly own properties.

11. Subsequent Events

During the third quarter of 2013, the Company agreed in three separate transactions to sell certain non-core assets, including substantially all of its remaining Barnett Shale assets, certain non-core assets in East Texas, and acreage in non-core areas of the Marcellus Shale, for an aggregate agreed upon sales price of $248.5 million and the assumption of certain liabilities and contractual obligations, subject to customary closing conditions and purchase price adjustments. In one of these transactions, the Company agreed to sell substantially all of its remaining Barnett Shale assets (the "Barnett Transaction") to affiliates of EnerVest Ltd. ("EnerVest") for an agreed upon purchase price of $218.0 million, subject to closing and post-closing purchase price adjustments and the assumption by EnerVest of certain liabilities and contractual obligations. The Barnett Transaction had an effective date of July 1, 2013. The Company closed the sale of its non-core East Texas assets in early September for $8.7 million. The Company closed the Barnett Transaction and the sale of its non-core Marcellus Shale assets in late October and as of October 31, 2013, the Company has received aggregate net proceeds related to these two asset sales totaling approximately $209.7 million. In addition, as a consequence of certain post-closing adjustments and holdbacks, the Company could receive up to an additional $23.8 million in cash proceeds related to such sales.

In connection with the Barnett Transaction, the Company entered into derivative instruments on behalf of EnerVest. These derivative instruments were novated to EnerVest upon the closing of the Barnett Transaction. As of September 30, 2013, these derivative instruments were in a net asset position and had a fair market value of $0.5 million.

Avista Transaction. Effective September 2011, the Company entered into a joint venture in the Utica Shale with Avista. On October 31, 2013, the Company completed the acquisition of acreage located primarily in Guernsey and Noble counties, Ohio from Avista. The transaction had an effective date of July 1, 2013, and the Company paid Avista $73.2 million in cash, subject to post-closing adjustments. The Company had an ownership in the working interest of the properties acquired through the Avista Utica Shale Joint Venture. The properties in the Avista Utica Joint Venture were held with an equal interest by the Company and Avista. The agreement provides for post-closing price and acreage adjustments and indemnities.

In connection with the Avista Transaction, the Company terminated the previously existing Avista Utica Shale Joint Venture agreements. After giving effect to the Avista Transaction, the Company and Avista remain working interest partners in the Utica Shale with the Company acting as the operator of the jointly owned properties which are now subject to standard joint operating agreements. The Company and Avista have established a new area of mutual interest that has been significantly reduced in coverage area and now applies only to certain of those areas in which the Company and Avista jointly own properties.