| Document and Entity Information | Sep. 27, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001610466 |
| Document Type | 8-K |
| Document Period End Date | Sep. 27, 2021 |
| Entity Registrant Name | Shell Midstream Partners, L.P. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-36710 |
| Entity Tax Identification Number | 46-5223743 |
| Entity Address, Address Line One | 150 N. Dairy Ashford |
| Entity Address, City or Town | Houston |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 77079 |
| City Area Code | (832) |
| Local Phone Number | 337-2034 |
| Security 12b Title | Common Units, Representing Limited Partner Interests |
| Trading Symbol | SHLX |
| Security Exchange Name | NYSE |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
