Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Proved oil and gas properties	$ 7,878,104	$ 7,058,782
Less: Accumulated depreciation, depletion, amortization and impairment	(2,853,353)	(2,395,153)
Proved oil and gas properties, net	5,024,751	4,663,629
Unproved oil and gas properties	1,034,085	780,173
Other property and equipment	1,151,772	868,746
Less: Accumulated depreciation	(183,499)	(139,062)
Other property and equipment, net	968,273	729,684
Total property, plant and equipment, net	$ 7,027,109	$ 6,173,486	$ 5,919,567