| Document and Entity Information Document | Feb. 22, 2021 |
| 8-K Cover [Abstract] | |
| Title of 12(b) Security | Common Stock, par value $1.00 |
| Entity Emerging Growth Company | false |
| Document Period End Date | Feb. 22, 2021 |
| Entity Incorporation, State or Country Code | DE |
| Document Type | 8-K |
| Entity Registrant Name | Marathon Oil Corporation |
| Entity File Number | 1-1513 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000101778 |
| Trading Symbol | MRO |
| Security Exchange Name | NYSE |
