Properties and Equipment, Net (Details 2) (USD $)	9 Months Ended				1 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Undeveloped oil and gas properties	Oct. 31, 2014 Subsequent event Undeveloped oil and gas properties	Oct. 31, 2014 Eagle Ford Shale in South Texas Subsequent event Proved and Unproved oil and gas properties
Property, Plant and Equipment [Line Items]
Minimum term of capitalization of exploratory well costs	1 year
Acquisition cost of proved and unproved oil and gas properties						$ 210,000,000
Total cash consideration paid for proved and unproved oil and gas properties as of closing date						186,200,000
Sale of undeveloped oil and gas properties	3,913,000	15,174,000			44,300,000
Total cash consideration received from sale of undeveloped oil and gas properties as of closing date					39,900,000
Net book value of assets held for sale	$ 5,130,213,000		$ 4,546,227,000	$ 21,500,000