| Cover | Dec. 16, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 16, 2024 |
| Current Fiscal Year End Date | --12-31 |
| Entity File Number | 000-56701 |
| Entity Registrant Name | New Mountain Net Lease Trust |
| Entity Central Index Key | 0002033695 |
| Entity Tax Identification Number | 99-6897976 |
| Entity Incorporation, State or Country Code | MD |
| Entity Address, Address Line One | 1633 Broadway, 48th Floor |
| 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 | 720-0300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
