v3.19.2
Cover Page - shares
6 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Cover page. [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity Registrant Name Evelo Biosciences, Inc.  
Entity Central Index Key 0001694665  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Emerging Growth Company true  
Small Business Entity true  
Entity Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   32,059,427