Oil and Gas Reserves Information (Unaudited) - Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Reserves (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Aug. 13, 2018		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows Relating to Proved Reserves:
Future Cash Flows	$ 8,054,092
Future Costs:
Production	(2,160,912)
Development and Abandonment	(1,800,335)
Future Income Taxes	(622,241)
Future Net Cash Flows	3,470,604
10% Discount Factor	(1,996,764)
Standardized Measure of Discounted Future Net Cash Flows	$ 1,473,840	$ 1,317,383	[1]
Predecessor
Cash Flows Relating to Proved Reserves:
Future Cash Flows		6,384,203		$ 3,588,764
Future Costs:
Production		(1,804,559)		(986,398)
Development and Abandonment		(1,945,141)		(672,559)
Future Income Taxes		(199,589)		5,239
Future Net Cash Flows		2,434,914		1,935,046
10% Discount Factor		(1,556,927)		(1,053,502)
Standardized Measure of Discounted Future Net Cash Flows		$ 877,987		881,544	$ 429,275	$ 372,139
Assets Held for Sale | Predecessor
Future Costs:
Standardized Measure of Discounted Future Net Cash Flows				$ 109,134

[1] The beginning Standardized Measure represents the contributed Bakken shale properties and the reserves of the Predecessor on a combined basis.