Debt - Revolving Credit Facility (Details) - Revolving Credit Facility $ in Millions	Mar. 31, 2024 USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 2,600
Optional limit increase	$ 939
Covenant, ratio of indebtedness to net capital, maximum	0.65
Ratio of indebtedness to net capital	0.25

Debt Instrument, Covenant, Ratio Of Indebtedness To Net Capital, Maximum

No definition available.

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Namespace Prefix:	mro_
Data Type:	xbrli:pureItemType
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Period Type:	instant

- Definition

Line of Credit Facility, Accordion Feature, Increase Limit

+ References

No definition available.

+ Details

Name:	mro_LineOfCreditFacilityAccordionFeatureIncreaseLimit
Namespace Prefix:	mro_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

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Balance Type:
Period Type: