v3.26.1
Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2025
Mar. 30, 2026
Document and Entity Information    
Document Type 10-K  
Document Annual Report true  
Document Transition Report false  
Document Period End Date Dec. 31, 2025  
Securities Act File Number 000-56701  
Entity Registrant Name New Mountain Net Lease Trust  
Entity Incorporation, State or Country Code MD  
Entity Tax Identification Number 99-6897976  
Entity Address, Address Line One 1633 Broadway  
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  
Title of 12(b) Security None  
Entity Well-known Seasoned Issuer No  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
ICFR Auditor Attestation Flag false  
Document Financial Statement Error Correction [Flag] false  
Entity Shell Company false  
Entity Public Float $ 0  
Entity Central Index Key 0002033695  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus FY  
Amendment Flag false  
Auditor Firm ID 34  
Auditor Name Deloitte & Touche LLP  
Auditor Location New York, New York  
Class A    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   9,159,016
Class F    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   11,674,001
Class I    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   8,549,336
Class E    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   6,715,822