Document And Entity Information - shares
3 Months Ended
Mar. 31, 2019
Apr. 30, 2019
Document And Entity Information [Abstract]    
Entity Registrant Name Kaleido BioSciences, Inc.  
Trading Symbol KLDO  
Entity Central Index Key 0001751299  
Current Fiscal Year End Date --12-31  
Document Type 10-Q  
Document Period End Date Mar. 31, 2019  
Amendment Flag false  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   29,807,703
Emerging Growth Company true  
Ex Transition Period false  
Entity Small Business false