Supplemental Oil and Gas Reserve Information - Developed and Undeveloped Oil and Gas Reserve (Details) MMBbls in Millions	May 03, 2021 MMBbls	Dec. 31, 2019 MMBoe MBbls Bcf
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume) \| MMBbls	583.5
Proved developed reserves (energy) \| MMBoe		129,200,000
Proved underdeveloped reserves \| MMBbls	22.6
Proved undeveloped reserves (energy) \| MMBoe		53,300,000
Oil
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume)		85,400,000
Proved underdeveloped reserves		34,300,000
Natural Gas Liquids
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume)		0
Proved underdeveloped reserves		0
Natural Gas
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume) \| Bcf		262,700,000
Proved underdeveloped reserves \| Bcf		113,500,000
Pro Forma
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (energy) \| MMBoe		178,900,000
Proved undeveloped reserves (energy) \| MMBoe		53,400,000
Pro Forma \| Oil
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume)		113,300,000
Proved underdeveloped reserves		34,000,000.0
Pro Forma \| Natural Gas Liquids
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume)		12,800,000
Proved underdeveloped reserves		1,600,000
Pro Forma \| Natural Gas
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume) \| Bcf		316,900,000
Proved underdeveloped reserves \| Bcf		106,500,000
Permian Basin Sale
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (energy) \| MMBoe		(16,700,000)
Proved undeveloped reserves (energy) \| MMBoe		(13,700,000)
Permian Basin Sale \| Oil
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume)		(13,200,000)
Proved underdeveloped reserves		(11,000,000.0)
Permian Basin Sale \| Natural Gas Liquids
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume)		0
Proved underdeveloped reserves		0
Permian Basin Sale \| Natural Gas
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume) \| Bcf		(20,800,000)
Proved underdeveloped reserves \| Bcf		(16,300,000)
Williston Basin Acquisition
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (energy) \| MMBoe		66,400,000
Proved undeveloped reserves (energy) \| MMBoe		13,800,000
Williston Basin Acquisition \| Oil
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume)		41,100,000
Proved underdeveloped reserves		10,700,000
Williston Basin Acquisition \| Natural Gas Liquids
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume)		12,800,000
Proved underdeveloped reserves		1,600,000
Williston Basin Acquisition \| Natural Gas
Oil and Gas Exploration and Production Industries [Line Items]
Proved developed reserves (volume) \| Bcf		75,000,000.0
Proved underdeveloped reserves \| Bcf		9,300,000

Oil and Gas Exploration and Production Industries [Line Items]

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Energy measure of interests in proved developed reserves of crude oil, including condensate and natural gas liquids, natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Form 20-F
-Section Item 18
-Subsection Instruction 2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123377692&loc=d3e61797-109447

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Net quantities of an enterprise's interests in proved developed reserves of either crude oil (including condensate and natural gas liquids), natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas as of the beginning and the end of the year. "Net" quantities of reserves include those relating to the enterprise's operating and nonoperating interests in properties. Quantities of reserves relating to royalty interests owned are included in "net" quantities if the necessary information is available to the enterprise. "Net" quantities does not include reserves relating to interests of others in properties owned by the enterprise. The unit of measure for reserve quantities is defined as "barrels" for oil and synthetic oil reserves or "cubic feet" or "cubic meters" for natural gas and synthetic gas reserves.

+ References

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Energy measure of proved undeveloped reserves of crude oil, including condensate and natural gas liquids, natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas.

+ References

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Net quantities of an enterprise's interests in proved undeveloped reserves of either crude oil (including condensate and natural gas liquids), natural gas, synthetic oil and gas, or other renewable natural resource that is intended to be upgraded into synthetic oil and gas as of the beginning and the end of the year. "Net" quantities of reserves include those relating to the enterprise's operating and nonoperating interests in properties. Quantities of reserves relating to royalty interests owned are included in "net" quantities if the necessary information is available to the enterprise. "Net" quantities does not include reserves relating to interests of others in properties owned by the enterprise. The unit of measure for reserve quantities is defined as "barrels" for oil and synthetic oil reserves or "cubic feet" or "cubic meters" for natural gas and synthetic gas reserves.

+ References

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