Supplemental Oil and Gas Information (Unaudited) - Schedule of Changes in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Reserves (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Extractive Industries [Abstract]
Beginning of year	$ 916,561	$ 1,113,029
Sale of oil and natural gas produced, net of production costs	(47,687)	(113,545)
Purchase of minerals in place	0	408,370
Extensions and discoveries	3,687	5,334
Changes in prices and costs	(548,429)	(623,592)
Previously estimated development costs incurred	49,144	84,341
Net changes in future development costs	89,997	110,892
Revisions of previous quantities	(150,245)	(183,300)
Accretion of discount	91,657	92,998
Change in production rates and other	(106,874)	22,034
End of year	$ 297,811	$ 916,561