| Cover | Aug. 02, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 2, 2021 |
| Entity Registrant Name | Black Stone Minerals, L.P. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-37362 |
| Entity Tax Identification Number | 47-1846692 |
| Entity Address, Address Line One | 1001 Fannin Street, Suite 2020 |
| Entity Address, City or Town | Houston, |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 77002 |
| City Area Code | (713) |
| Local Phone Number | 445-3200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Units Representing Limited Partner Interests |
| Trading Symbol | BSM |
| Security Exchange Name | NYSE |
| Entity Central Index Key | 0001621434 |
| Amendment Flag | false |
