| Document and Entity Information | Sep. 16, 2024 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0002006758 |
| Document Type | 8-K |
| Document Period End Date | Sep. 16, 2024 |
| Entity Registrant Name | Middle Market Apollo Institutional Private Lending |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 000-56645 |
| Entity Tax Identification Number | 93-4353274 |
| Entity Address, Address Line One | 9 West 57th Street |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10019 |
| City Area Code | (212) |
| Local Phone Number | 515-3450 |
| 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 | false |
