| Document and Entity Information | Dec. 18, 2024 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001736035 |
| Document Type | 8-K |
| Document Period End Date | Dec. 18, 2024 |
| Entity Registrant Name | Blackstone Secured Lending Fund |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 814-01299 |
| Entity Tax Identification Number | 82-7020632 |
| Entity Address, Address Line One | 345 Park Avenue |
| Entity Address, Address Line Two | 31st Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10154 |
| City Area Code | (212) |
| Local Phone Number | 503-2100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Shares of Beneficial Interest, $0.001 par value per share |
| Trading Symbol | BXSL |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
