Acquisition and Development Agreement	9 Months Ended
Sep. 30, 2011
Acquisition and Development Agreement [Abstract]
Acquisition and Development Agreement	Acquisition and Development Agreement In June 2011, the Company entered into an Acquisition and Development Agreement (the “Acquisition and Development Agreement”) with Mitsui E&P Texas LP (“Mitsui”), an indirect subsidiary of Mitsui & Co., Ltd. Pursuant to the Acquisition and Development Agreement, the Company agreed to transfer to Mitsui a 12.5 percent working interest in certain non-operated oil and gas assets representing approximately 39,000 net acres in Dimmit, LaSalle, Maverick and Webb Counties, Texas. The agreement also provides for the conveyance of one-half of the Company’s ownership in related gathering assets for the reimbursement by Mitsui of 50 percent of costs incurred on those assets and paid by the Company through the closing date. If consummated, the effective date of the transfer would be March 1, 2011. As consideration for the oil and gas interests transferred, Mitsui has agreed to pay, or carry, 90 percent of certain drilling and completion costs attributable to the Company's remaining interest in these assets following the closing of the transaction, until Mitsui has expended an aggregate $680.0 million on behalf of the Company. The Company estimates it will take three to four years to fully utilize the carry, based on the operator’s announced current drilling plans. Mitsui would also reimburse the Company for capital expenditures and other costs, net of revenues, that the Company paid and attributable to the transferred interest during the period between March 1, 2011 and the closing date. The Company would apply these reimbursed costs to the remaining ten percent of the Company’s drilling and completion costs for the affected acreage. The transaction was initially expected to close in the third quarter of 2011, subject to the satisfaction of closing conditions. Subsequent to September 30, 2011, the Company and Mitsui mutually agreed to extend the outside date for closing to December 23, 2011 to allow the parties to continue efforts to satisfy outstanding closing conditions, including obtaining required consents. There can be no assurance that this transaction will be completed in the anticipated time frame, or at all.

Acquisition and Development Agreement

In June 2011, the Company entered into an Acquisition and Development Agreement (the “Acquisition and Development Agreement”) with Mitsui E&P Texas LP (“Mitsui”), an indirect subsidiary of Mitsui & Co., Ltd. Pursuant to the Acquisition and Development Agreement, the Company agreed to transfer to Mitsui a 12.5 percent working interest in certain non-operated oil and gas assets representing approximately 39,000 net acres in Dimmit, LaSalle, Maverick and Webb Counties, Texas. The agreement also provides for the conveyance of one-half of the Company’s ownership in related gathering assets for the reimbursement by Mitsui of 50 percent of costs incurred on those assets and paid by the Company through the closing date. If consummated, the effective date of the transfer would be March 1, 2011. As consideration for the oil and gas interests transferred, Mitsui has agreed to pay, or carry, 90 percent of certain drilling and completion costs attributable to the Company's remaining interest in these assets following the closing of the transaction, until Mitsui has expended an aggregate $680.0 million on behalf of the Company. The Company estimates it will take three to four years to fully utilize the carry, based on the operator’s announced current drilling plans. Mitsui would also reimburse the Company for capital expenditures and other costs, net of revenues, that the Company paid and attributable to the transferred interest during the period between March 1, 2011 and the closing date. The Company would apply these reimbursed costs to the remaining ten percent of the Company’s drilling and completion costs for the affected acreage. The transaction was initially expected to close in the third quarter of 2011, subject to the satisfaction of closing conditions. Subsequent to September 30, 2011, the Company and Mitsui mutually agreed to extend the outside date for closing to December 23, 2011 to allow the parties to continue efforts to satisfy outstanding closing conditions, including obtaining required consents. There can be no assurance that this transaction will be completed in the anticipated time frame, or at all.