v3.7.0.1
Document and Entity Information - shares
6 Months Ended
Jun. 30, 2017
Aug. 10, 2017
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2017  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q2  
Trading Symbol ALRN  
Entity Registrant Name AILERON THERAPEUTICS INC  
Entity Central Index Key 0001420565  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   14,714,816