Acquisitions (Schedule of Revenues and Lease Operating Expenses Attributable to the ST 41 Interests, the ASOP Properties and the Main Pass Interests) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Hilcorp Properties Acquisition [Member]
Business Acquisition [Line Items]
Revenue	$ 208,241	$ 37,978
Lease operating expenses	74,404	10,982
South Timbalier Acquisition [Member]
Business Acquisition [Line Items]
Revenue	11,189	9,262
Lease operating expenses	2,468	1,760
ASOP and Main Pass Acquisition [Member]
Business Acquisition [Line Items]
Revenue	328,070	175,538	125,975
Lease operating expenses	33,978	26,467	17,161
West Delta 29 Acquisition [Member]
Business Acquisition [Line Items]
Revenue	3,011
Lease operating expenses	$ 44