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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Production and ad valorem taxes									$ 10,141	$ 8,490	$ 7,927
Total operating expenses	$ 123,590	$ 108,929	$ 92,989	$ 95,651	$ 108,431	$ 94,338	$ 80,589	$ 87,632	421,159	370,990	352,436
Operating loss	47,618	21,194	10,633	14,541	(4,375)	(2,789)	5,602	14,231	93,986	12,669	(117,402)
Loss before income taxes									18,826	8,525	(206,189)
Income tax benefit (expense)											(546)
Net loss	$ 36,490	$ 3,998	$ (19,036)	$ (2,626)	$ (13,122)	$ (16,694)	$ 11,494	$ 26,847	$ 18,826	$ 8,525	$ (206,735)
Basic and diluted loss per share											$ (12.84)
As Reported [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Production and ad valorem taxes											$ 4,998
Total operating expenses											349,507
Operating loss											(114,473)
Loss before income taxes											(203,260)
Net loss											$ (203,806)
Basic and diluted loss per share											$ (12.60)
Adjustment [Member]
Quantifying Misstatement In Current Year Financial Statements [Line Items]
Production and ad valorem taxes											$ 2,929
Total operating expenses											2,929
Operating loss											(2,929)
Loss before income taxes											(2,929)
Net loss											$ (2,929)
Basic and diluted loss per share											$ (0.24)