| Cover Page | Jan. 18, 2021 | Dec. 31, 2020 |
| Cover [Abstract] | ||
| Document Type | 8-K/A | |
| Document Period End Date | Jan. 18, 2021 | |
| Entity Registrant Name | OASIS PETROLEUM INC. | |
| Entity Incorporation, State or Country Code | DE | |
| Entity File Number | 001-34776 | |
| Entity Tax Identification Number | 80-0554627 | |
| Entity Address, Address Line One | 1001 Fannin Street | |
| Entity Address, Address Line Two | Suite 1500 | |
| Entity Address, City or Town | Houston | |
| Entity Address, State or Province | TX | |
| Entity Address, Postal Zip Code | 77002 | |
| City Area Code | 281 | |
| Local Phone Number | 404-9500 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Title of 12(b) Security | Common Stock | |
| Trading Symbol | OAS | |
| Security Exchange Name | NASDAQ | |
| Entity Emerging Growth Company | false | |
| Entity Central Index Key | 0001486159 | |
| Amendment Flag | false | |
| Current Fiscal Year End Date |
