Equity and Share-Based Compensation (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation, Post-Initial Public Offering
Total share-based compensation expense	$ 5,713,000	$ 2,459,000	$ 53,744,000
Capitalized qualifying share-based compensation costs to oil and gas properties	1,400,000	200,000
Restricted and unrestricted Petroleum Inc. shares and Holdings LLC units
Share-based Compensation, Post-Initial Public Offering
Total share-based compensation expense			53,744,000
2012 LTIP | Restricted stock awards
Share-based Compensation, Post-Initial Public Offering
Total share-based compensation expense	$ 5,713,000	$ 2,459,000