Supplemental Oil and Gas Information (Unaudited) -Standardized Measure of Discounted Future Net Cash Flows (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 04, 2017	Dec. 31, 2016
Supplemental Oil And Gas Reserve Information [Line Items]
Future cash inflows	$ 5,146,288	$ 6,000,268	$ 5,149,623
Future production costs	(2,917,262)	(3,280,778)	(2,982,035)
Future development costs	(567,423)	(474,413)	(530,133)
Future income tax expense	0	0	0
Future net cash flows for estimated timing of cash flows	1,661,603	2,245,077	1,637,455
10% annual discount for estimated timing of cash flows	(745,042)	(1,132,048)	(869,784)
Standardized measure of discounted future net cash flows	$ 916,561	$ 1,113,029	$ 767,671	$ 691,089
Predecessor [Member]
Supplemental Oil And Gas Reserve Information [Line Items]
Future cash inflows				5,246,487
Future production costs				(3,275,952)
Future development costs				(492,610)
Future income tax expense				0
Future net cash flows for estimated timing of cash flows				1,477,925
10% annual discount for estimated timing of cash flows				(786,836)
Standardized measure of discounted future net cash flows				$ 691,089	$ 395,841