Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2020
Apr. 30, 2020
Document and Entity Information    
Document Type 10-Q  
Document Period End Date Mar. 31, 2020  
Entity Registrant Name RUBIUS THERAPEUTICS, INC.  
Entity Current Reporting Status Yes  
Entity Filer Category Accelerated Filer  
Entity Interactive Data Current Yes  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   80,476,102
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q1  
Entity Central Index Key 0001709401  
Amendment Flag false