Acquisitions - Narrative (Details) - Ensign Natural Resources a in Thousands, $ in Millions		3 Months Ended	12 Months Ended
Dec. 27, 2022 USD ($) a well	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Business Acquisition [Line Items]
Cash consideration	$ 3,000
Net proved and unproved acres \| a	130
Average working interest, percent	97.00%
Number of wells acquired \| well	700,000,000
Acquisition related costs			$ 18
Business combination, consideration transferred, increase in ownership interest		$ 135

Business Combination, Assets Acquired, Average Working Interest, Percent

No definition available.

Name:	mro_BusinessCombinationAssetsAcquiredAverageWorkingInterestPercent
Namespace Prefix:	mro_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Business Combination, Assets Acquired, Net Proved and Unproved Acres

+ References

No definition available.

+ Details

Name:	mro_BusinessCombinationAssetsAcquiredNetProvedAndUnprovedAcres
Namespace Prefix:	mro_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Business Combination, Consideration Transferred, Increase in Ownership Interest

+ References

No definition available.

+ Details

Name:	mro_BusinessCombinationConsiderationTransferredIncreaseInOwnershipInterest
Namespace Prefix:	mro_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business Combination, Number of Wells Acquired

+ References

No definition available.

+ Details

Name:	mro_BusinessCombinationNumberOfWellsAcquired
Namespace Prefix:	mro_
Data Type:	xbrli:integerItemType
Balance Type:	na
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

No definition available.

+ Details

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

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI https://asc.fasb.org/extlink&oid=123586518&loc=d3e1043-128460

+ Details

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI https://asc.fasb.org/extlink&oid=126975305&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=mro_EnsignNaturalResourcesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: