Fair Value Measurements - Reconciliation of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis using Significant Unobservable Inputs (Parenthetical) (Details)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Fair value, level 3 transfers out description	During the years ended December 31, 2012 and 2010, the Company did not have any transfers between Level 1, Level 2 or Level 3 fair value measurements.	Fair values related to the Company’s oil and natural gas fixed price swaps, natural gas collars and interest rate swap were transferred from Level 3 to Level 2 in the fourth quarter of 2011 due to enhancements to the Company’s internal valuation process, including the use of observable inputs to assess the fair value.

Fair Value Measurements - Reconciliation of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis using Significant Unobservable Inputs (Parenthetical) (Details)

12 Months Ended

Dec. 31, 2012

Dec. 31, 2011

Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]

Fair value, level 3 transfers out description

During the years ended December 31, 2012 and 2010, the Company did not have any transfers between Level 1, Level 2 or Level 3 fair value measurements.

Fair values related to the Company’s oil and natural gas fixed price swaps, natural gas collars and interest rate swap were transferred from Level 3 to Level 2 in the fourth quarter of 2011 due to enhancements to the Company’s internal valuation process, including the use of observable inputs to assess the fair value.