Supplemental Oil and Gas Reserve Information - Unaudited - Additional Information (Detail)	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2020 MMBoe	Nov. 19, 2020 MMBoe	Dec. 31, 2020 MBoe	Dec. 31, 2020	Dec. 31, 2020 MMBoe	Dec. 31, 2020 $ / bbl	Dec. 31, 2020 $ / MMBTU	Dec. 31, 2019 MBoe	Dec. 31, 2019	Dec. 31, 2019 MMBoe	Dec. 31, 2019 $ / bbl	Dec. 31, 2019 $ / MMBTU	Dec. 31, 2018 MBoe	Dec. 31, 2018	Dec. 31, 2018 MMBoe	Dec. 31, 2018 $ / bbl	Dec. 31, 2018 $ / MMBTU	Dec. 31, 2017 MMBoe
Reserve Quantities [Line Items]
Net positive (negative) revisions of previous estimates (MMBoe)			(86,251)					(63,349)		(63,300)			(16,850)		(16,900)
Percentage of net positive (negative) revisions				(30.00%)					(20.00%)					(5.00%)
Positive (negative) revisions of previous estimates - proved developed reserves (MMBoe)															(20,200)
Additions due to extensions and discoveries (MMBoe)			6,021		6,000.0			63,861		63,900			38,358		38,400
Estimated extensions and discoveries of reserves associated with new wells (MMBoe) | MBoe			3,200					10,300					9,000.0
Percentage of reserves produced from wells in certain formations									60.00%					77.00%
Additional proved undeveloped reserves (MMBoe)					2,800					53,600					29,400
Percentage of proved undeveloped reserves														76.00%
Divested reserves associated with non-operated properties (MMBoe)	0	0						2,531		2,500			15,926		15,900
Purchases of reserves in place (MMBoe)										0			32,873					32,900
Unweighted arithmetic average first-day-of-the-month prices for oil (in dollars per Bbl) | $ / bbl						39.54					55.85					65.66
Unweighted arithmetic average first-day-of-the-month prices for natural gas (in dollars per MMBtu) | $ / MMBTU							2.03					2.62					3.16
Revision of Previous Estimate Due to Realized Prices
Reserve Quantities [Line Items]
Net positive (negative) revisions of previous estimates (MMBoe)					(29.3)					11,200					14,400
Positive (negative) revisions of previous estimates - proved developed reserves (MMBoe)					(31.9)					(9,600)					12,200
Positive (negative) revisions of previous estimates - proved undeveloped reserves (MMBoe)					2.6										2,200
Revision Due to Performance
Reserve Quantities [Line Items]
Net positive (negative) revisions of previous estimates (MMBoe)										(51,200)					(42,300)
Positive (negative) revisions of previous estimates - proved developed reserves (MMBoe)										(30,200)					(33,000.0)
Positive (negative) revisions of previous estimates - proved undeveloped reserves (MMBoe)										21,100					(9,300)
Revision of Previous Estimate Due to (Mis)Alignment With Development Plan
Reserve Quantities [Line Items]
Net positive (negative) revisions of previous estimates (MMBoe)					(60.1)					(7,600)					(9,400)
Positive (negative) revisions of previous estimates - proved undeveloped reserves (MMBoe)					(54.5)					(7,000.0)					(9,400)
Revision of Previous Estimate Due to Lower Operating Expenses
Reserve Quantities [Line Items]
Net positive (negative) revisions of previous estimates (MMBoe)					(1.5)					(6,700)
Positive (negative) revisions of previous estimates - proved developed reserves (MMBoe)										5,100
Positive (negative) revisions of previous estimates - proved undeveloped reserves (MMBoe)										(1,700)
Revisions Due to Addition of Proved Undeveloped Reserves (PUDs)
Reserve Quantities [Line Items]
Net positive (negative) revisions of previous estimates (MMBoe)					(5.6)										14,700
Positive (negative) revisions of previous estimates - proved undeveloped reserves (MMBoe)															14,700
Revision of Previous Estimate Due to Ownership Adjustments
Reserve Quantities [Line Items]
Net positive (negative) revisions of previous estimates (MMBoe)															5,400
Positive (negative) revisions of previous estimates - proved undeveloped reserves (MMBoe)															5,600
Bakken or Three Forks Formations Area
Reserve Quantities [Line Items]
Percentage of reserves produced from wells in certain formations				1.00%
Percentage of proved undeveloped reserves									63.00%
Delaware Basin
Reserve Quantities [Line Items]
Percentage of reserves produced from wells in certain formations				99.00%					40.00%					23.00%
Percentage of proved undeveloped reserves									37.00%					24.00%