Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2019
Amendment Flag	false
Entity Registrant Name	Marathon Oil Corporation
Entity Central Index Key	0000101778
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock Shares Outstanding		817,916,151