Long-Term Debt and Notes Payable - Additional Information (Details) - USD ($)		3 Months Ended		6 Months Ended
	Sep. 02, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Apr. 16, 2015	Dec. 31, 2014	Nov. 17, 2014
Debt Instrument [Line Items]
Cross default provision, threshold amount		$ 10,000,000		$ 10,000,000
Initial borrowing base		$ 1,600,000,000		$ 1,600,000,000			$ 2,000,000,000
Loan limit percentage (less than)		10.00%		10.00%
Credit facility cross default provision, threshold amount		$ 75,000,000		$ 75,000,000
Interest expense		11,244,000	$ 7,964,000	23,002,000	$ 15,852,000
Capitalized interest expense		$ 0	$ 37,000	$ 32,000	$ 37,000
Commitment fee (basis points)				0.30%
Syndicated Credit Facility | Credit Facility, September 2, 2014
Debt Instrument [Line Items]
Term of credit facility	5 years
Initial borrowing base	$ 2,100,000,000
Maximum borrowing capacity	$ 1,500,000,000					$ 1,600,000,000		$ 2,000,000,000
Debt covenant, debt to EBITDAX ratio		4.0		4.0
Debt covenant, current assets to current liabilities ratio		1.0		1.0
Debt covenant, minimum net present value of proved reserves to consolidated debt, ratio		1.50		1.50