Summary of Significant Accounting Policies - Additional Information 1 (Detail)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2015 ExecutiveOfficers	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Operations And Summary Of Significant Accounting Policies [Line Items]
Impairment charges for unevaluated properties		$ 5,100,000		$ 68,600,000	$ 0
Impairment charges related to oil and gas properties		544,700,000		547,100,000
Net proceeds from sale of oil and gas property		102,700,000
Loss on sale of oil and gas properties		111,800,000		$ 111,778,000
Acquired interest in corporate airplane	20.00%			20.00%
Pre-Acquisition Company interest in corporate airplane	80.00%
Number of executive officers | ExecutiveOfficers	2
Pre-Acquisition executive officers interest in corporate airplane	20.00%
Consideration paid for interest in corporate airplane				$ 1,700,000
Cash flow hedges derivative instruments		0		0
(Payments) receipts on derivative financial instruments				(391,000)	5,702,000
Derivative Financial Instruments - Current Asset		1,314,000		1,314,000
Derivative Financial Instruments						$ 0
Natural Gas
Operations And Summary Of Significant Accounting Policies [Line Items]
Total gain (loss) on oil price swaps		1,100,000		1,700,000
(Payments) receipts on derivative financial instruments		$ 400,000		$ 400,000
Oil
Operations And Summary Of Significant Accounting Policies [Line Items]
Total gain (loss) on oil price swaps			$ 12,000,000		(2,800,000)
(Payments) receipts on derivative financial instruments			$ (400,000)		$ (5,700,000)