Document And Entity Information - shares
6 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Document And Entity Information [Abstract]    
Entity Registrant Name Kaleido Biosciences, Inc.  
Entity Central Index Key 0001751299  
Current Fiscal Year End Date --12-31  
Document Type 10-Q  
Document Period End Date Jun. 30, 2019  
Amendment Flag false  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   29,832,693
Entity Shell Company false  
Entity Current Reporting Status Yes  
Emerging Growth Company true  
Ex Transition Period false  
Entity Small Business false