Summary of Significant Accounting Policies - Summary of Reconciliation of Amounts in Previously Reported Consolidated Financial Statements - Statement of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Production and ad valorem taxes									$ 8,490	$ 7,927	$ 3,722
Total operating expenses	$ 108,431	$ 94,338	$ 80,589	$ 87,632	$ 89,527	$ 78,678	$ 84,017	$ 100,214	370,990	352,436	1,234,907
Operating loss	(4,375)	(2,789)	5,602	14,231	(5,644)	(24,199)	(36,951)	(50,608)	12,669	(117,402)	(979,586)
Loss before income taxes									8,525	(206,189)	(1,035,957)
Income tax benefit (expense)										(546)	74,166
Net loss	$ (13,122)	$ (16,694)	$ 11,494	$ 26,847	$ (62,089)	$ (25,949)	$ (73,163)	$ (45,534)	$ 8,525	$ (206,735)	$ (961,791)
Basic and diluted loss per share					$ (0.23)	$ (0.10)	$ (0.33)	$ (0.20)		$ (0.86)	$ (4.41)
As Reported [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Production and ad valorem taxes										$ 4,998	$ 11,621
Total operating expenses										349,507	1,242,806
Operating loss										(114,473)	(987,485)
Loss before income taxes										(203,260)	(1,043,856)
Income tax benefit (expense)											72,446
Net loss										$ (203,806)	$ (971,410)
Basic and diluted loss per share										$ (0.84)	$ (4.46)
Adjustment [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Production and ad valorem taxes										$ 2,929	$ (7,899)
Total operating expenses										2,929	(7,899)
Operating loss										(2,929)	7,899
Loss before income taxes										(2,929)	7,899
Income tax benefit (expense)											1,720
Net loss										$ (2,929)	$ 9,619
Basic and diluted loss per share										$ (0.02)	$ 0.05