Cover - shares	9 Months Ended
	Sep. 30, 2020	Oct. 31, 2020
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	1-1513
Entity Registrant Name (tagged on cover)	Marathon Oil Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	25-0996816
Entity Address, Address Line One	5555 San Felipe Street,
Entity Address, City or Town	Houston,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77056-2723
City Area Code	(713)
Local Phone Number	629-6600
Title of 12(b) Security	Common Stock, par value $1.00
Trading Symbol	MRO
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		789,391,520
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2020
Amendment Flag	false
Entity Central Index Key	0000101778
Current Fiscal Year End Date	--12-31