Long-Term Debt - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended				9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Revolving credit facility	Oct. 28, 2013 Revolving credit facility	Sep. 30, 2014 Revolving credit facility Minimum	Sep. 30, 2014 Revolving credit facility Maximum	Sep. 30, 2014 Revolving credit facility through December 31, 2013 Maximum	Sep. 30, 2014 Revolving credit facility through maturity Maximum	Sep. 30, 2014 Revolving credit facility Letter of Credit	Sep. 30, 2014 Previous Revolving Credit Facility	Jul. 31, 2014 Previous Revolving Credit Facility	Oct. 28, 2013 Previous Revolving Credit Facility	Sep. 30, 2014 7.25% Senior Notes due 2019	Dec. 31, 2013 7.25% Senior Notes due 2019	Sep. 30, 2014 7.25% Senior Notes due 2019 Group One	Sep. 30, 2014 7.25% Senior Notes due 2019 Group Two	Sep. 30, 2014 Senior Notes due 2020	Dec. 31, 2013 Senior Notes due 2020
Debt Disclosure [Line Items]
Gains (Losses) on Extinguishment of Debt	$ 0	$ 0	$ 0	$ (29,157,000)
Senior Notes, Noncurrent															300,000,000	300,000,000			775,000,000	775,000,000
Line Of Credit Facility Borrowing Base													437,500,000	475,000,000
Maximum borrowing capacity						450,000,000					20,000,000
Optional additional borrowing					150,000,000
Letter of credit amount outstanding												1,700,000
Available borrowing capacity												$ 435,800,000
Credit facility interest rate option one, applicable margin rate over Adjusted LIBOR							1.50%	2.50%
Credit facility interest rate option two, base rate over federal funds effective rate					0.50%
Debt Instrument, Description of Variable Rate Basis			one-month Adjusted LIBOR
Credit facility interest rate option two, base rate over one-month Adjusted LIBOR					1.00%
Credit facility interest rate option two, applicable margin rate					1.50%		0.50%	1.50%
Commitment fees for undrawn credit facility							0.375%	0.50%
LIne of Credit Facility, Commitment Fee Percentage at Period End					0.375%
Line of Credit Facility, Interest Rate at Period End					1.6875%
Line of Credit Facility, Interest Rate at Period End, LIBOR component					0.1875%
Current ratio							1.0
Debt to EBITDAX ratio									4.25	4.0
Annual interest rate															7.25%				8.50%
Redemption option, percent of principal																	103.625%	100.00%