Subsequent Events	3 Months Ended
Mar. 31, 2012
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events The Company has evaluated the period after the balance sheet date, noting no subsequent events or transactions that required recognition or disclosure in the financial statements, other than as noted below. Senior secured revolving line of credit. On April 3, 2012, the Company entered into a sixth amendment to its Amended Credit Facility (the "Sixth Amendment") among OPNA, as borrower, OP LLC, OPM, OWS and the Company, as guarantors, the lenders party thereto and BNP Paribas, as administrative agent. In connection with the Sixth Amendment, the semi-annual redetermination of the Company's borrowing base was completed on April 3, 2012, which resulted in the borrowing base of the Amended Credit Facility increasing from $350 million to $500 million. The Sixth Amendment also added two new lenders to the bank group. All other terms and conditions of the Amended Credit Facility remained the same (see Note 7 — Long-Term Debt). Effective April 20, 2012, the Company executed an agreement consenting to the resignation of BNP Paribas as the administrative agent and a lender under the Amended Credit Facility. Wells Fargo was appointed successor administrative agent and assumed the credit commitment of BNP Paribas. BNP Paribas remains as a counterparty for the Company's commodity derivative instruments. Fracturing services. In April 2012, the Company entered into an agreement with one of its third party fracturing service companies to terminate the original contract that had an initial term greater than one year. The Company did not pay any early contract termination fees related to this termination agreement. Derivative instruments. In May 2012, the Company entered into new two-way and three-way costless collar options, all of which settle monthly based on the West Texas Intermediate crude oil index price, for a total notional amount of 306,000 barrels in 2012, 730,000 barrels in 2013, 730,000 barrels in 2014, and 62,000 barrels in 2015. These derivative instruments do not qualify for and were not designated as hedging instruments for accounting purposes.

13. Subsequent Events

The Company has evaluated the period after the balance sheet date, noting no subsequent events or transactions that required recognition or disclosure in the financial statements, other than as noted below.

Senior secured revolving line of credit. On April 3, 2012, the Company entered into a sixth amendment to its Amended Credit Facility (the "Sixth Amendment") among OPNA, as borrower, OP LLC, OPM, OWS and the Company, as guarantors, the lenders party thereto and BNP Paribas, as administrative agent. In connection with the Sixth Amendment, the semi-annual redetermination of the Company's borrowing base was completed on April 3, 2012, which resulted in the borrowing base of the Amended Credit Facility increasing from $350 million to $500 million. The Sixth Amendment also added two new lenders to the bank group. All other terms and conditions of the Amended Credit Facility remained the same (see Note 7 — Long-Term Debt). Effective April 20, 2012, the Company executed an agreement consenting to the resignation of BNP Paribas as the administrative agent and a lender under the Amended Credit Facility. Wells Fargo was appointed successor administrative agent and assumed the credit commitment of BNP Paribas. BNP Paribas remains as a counterparty for the Company's commodity derivative instruments.

Fracturing services. In April 2012, the Company entered into an agreement with one of its third party fracturing service companies to terminate the original contract that had an initial term greater than one year. The Company did not pay any early contract termination fees related to this termination agreement.

Derivative instruments. In May 2012, the Company entered into new two-way and three-way costless collar options, all of which settle monthly based on the West Texas Intermediate crude oil index price, for a total notional amount of 306,000 barrels in 2012, 730,000 barrels in 2013, 730,000 barrels in 2014, and 62,000 barrels in 2015. These derivative instruments do not qualify for and were not designated as hedging instruments for accounting purposes.