Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Jul. 29, 2019
Document and Entity Information [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  
Trading Symbol TBIO  
Entity Registrant Name Translate Bio, Inc.  
Entity Central Index Key 0001693415  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Shell Company false  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period true  
Entity Address, State or Province DE  
Entity Interactive Data Current Yes  
Title of 12(b) Security Common stock  
Security Exchange Name NASDAQ  
Entity Common Stock, Shares Outstanding   51,010,368