Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 31, 2019
Document and Entity Information [Abstract]
Title of 12(b) Security	Common Stock, par value $1.00
Document Type	10-Q
Entity File Number	1-1513
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2019
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2019
Amendment Flag	false
Entity Registrant Name (tagged on cover)	Marathon Oil Corporation
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
Trading Symbol	MRO
Security Exchange Name	NYSE
Entity Central Index Key	0000101778
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		804,042,151
Document Transition Report	false
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Small Business	false
Entity Tax Identification Number	25-0996816
Entity Interactive Data Current	Yes