v3.26.1
Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2026
May 07, 2026
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Mar. 31, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Entity Registrant Name Lexeo Therapeutics, Inc.  
Entity Central Index Key 0001907108  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity File Number 001-41855  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 85-4012572  
Entity Address, Address Line One 345 Park Avenue South  
Entity Address, Address Line Two Floor 6  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10010  
City Area Code 212  
Local Phone Number 547-9879  
Entity Small Business true  
Entity Filer Category Non-accelerated Filer  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Title of 12(b) Security Common Stock ($0.0001 par value)  
Trading Symbol LXEO  
Security Exchange Name NASDAQ  
Document Quarterly Report true  
Document Transition Report false  
Entity Shell Company false  
Entity Interactive Data Current Yes  
Entity Common Stock, Shares Outstanding   78,521,634