Revenue from Contracts with Customers - Summary of New Accounting Pronouncements and Changes in Accounting Principles (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Operating expenses
Gathering, transportation and processing	$ 0	$ 4,890	$ 0		$ 11,360
Net loss	(301,240)	10,710	(288,916)	[1]	28,837
Under ASC 605
Operating expenses
Gathering, transportation and processing	11,844		30,396
Net loss	(301,240)		(288,916)
Oil sales
Revenues
Revenues	74,987	$ 16,701	197,356		$ 45,702
Oil sales | Under ASC 605
Revenues
Revenues	75,062		197,431
Natural gas sales
Revenues
Revenues	18,059		48,956
Natural gas sales | Under ASC 605
Revenues
Revenues	21,739		60,919
Natural gas liquid sales
Revenues
Revenues	27,106		65,377
Natural gas liquid sales | Under ASC 605
Revenues
Revenues	35,195		83,735
Accounting Standards Update 2014-09 | Increase/ (decrease)
Operating expenses
Gathering, transportation and processing	(11,844)		(30,396)
Net loss	0		0
Accounting Standards Update 2014-09 | Oil sales | Increase/ (decrease)
Revenues
Revenues	(75)		(75)
Accounting Standards Update 2014-09 | Natural gas sales | Increase/ (decrease)
Revenues
Revenues	(3,680)		(11,963)
Accounting Standards Update 2014-09 | Natural gas liquid sales | Increase/ (decrease)
Revenues
Revenues	$ (8,089)		$ (18,358)

[1] Amounts are allocated to stockholders' equity and members' equity to reflect the Reorganization. See Note 10 – Equity for discussion of the Reorganization.