| Cover Page | Sep. 29, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Dec. 22, 2020 |
| Entity Registrant Name | OASIS MIDSTREAM PARTNERS LP |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-38212 |
| Entity Tax Identification Number | 47-1208855 |
| 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 |
| Title of 12(b) Security | Common units representing limited partner interests |
| Trading Symbol | OMP |
| Security Exchange Name | NASDAQ |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
| Entity Central Index Key | 0001652133 |
| Amendment Flag | false |
