Supplemental Information On Oil And Gas Exploration And Production Activities (Unaudited) - Narrative (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) MMBTU MBoe $ / MMBTU $ / bbl	Dec. 31, 2019 USD ($) MMBTU MBoe $ / bbl $ / MMBTU	Dec. 31, 2018 USD ($) MBoe
Reserve Quantities [Line Items]
Additions to oil and gas properties | $	$ 67,848	$ 210,907
Natural gas liquids prices used to value reserves | $ / bbl	11.61	16.17
Oil prices used to value reserves (in dollars per barrel) | $ / bbl	38.90
Natural gas prices used to value reserves (in dollars per MMBtu) | $ / MMBTU	0.97
Natural gas liquids prices used to value reserves (in dollars per barrel) | $ / bbl	11.61
Proved extensions and discoveries	860,000	5,065,000
Downward revision to previous estimate	10,691,000	4,642,000
Sales of minerals in place		(32,000)
Conversion period of proved undeveloped reserves into proved developed producing reserves		5 years	5 years
Estimated capital expenditures of proved undeveloped reserves | $		$ 111,100	$ 103,800
Estimated proved undeveloped reserves, conversions to developed, gross		28,000	30
Estimated proved undeveloped reserves, conversions to developed, net		17,600	12,300
Estimated conversion of proved undeveloped reserves into proved developed producing reserves		11,300,000	9,900
Capital expenditures of proved undeveloped reserves | $	$ 67,800	$ 111,500
Modified proved undeveloped reserves, conversions to developed, gross	18,000	32,000
Modified proved undeveloped reserves, conversions to developed, net	10,300	13.4
Modified conversion of proved undeveloped reserves into proved developed producing reserves	(8,200,000)	10.3
Development plan	5 years
Reclassifications	11,900,000
Extensions and discoveries		1,230,000
Revisions	(14,038,000)	(3,362,000)
Remaining Revisions Of Proved Undeveloped Previous Estimate Energy		2,100,000
Non-Cancelable Agreement
Reserve Quantities [Line Items]
Holding pipeline capacity | MMBTU	10,000	10,000
Earthstone Energy Credit Agreement
Reserve Quantities [Line Items]
Capitalized costs associated with borrowings | $	$ 0	$ 1,600
Midland Basin
Reserve Quantities [Line Items]
Proved extensions and discoveries	860,000.0
Williston Basin
Reserve Quantities [Line Items]
Sales of minerals in place		(32,000.0)
Henry Hub Spot Price
Reserve Quantities [Line Items]
Unweighted average of first of the month prices of natural gas | $ / MMBTU	1.99	2.58
West Texas Intermediate Spot Price
Reserve Quantities [Line Items]
Unweighted average of first of the month prices of oil | $ / bbl	39.57	55.69
New Wells
Reserve Quantities [Line Items]
Additions to oil and gas properties | $	$ 800	$ 100
Operated Eagle Ford and Non-operated Bakken Properties
Reserve Quantities [Line Items]
Proved extensions and discoveries		5,100,000