v3.19.1
Document and Entity Information - shares
3 Months Ended
Mar. 31, 2019
May 07, 2019
Document and Entity Information    
Entity Registrant Name Aclaris Therapeutics, Inc.  
Entity Central Index Key 0001557746  
Document Type 10-Q  
Document Period End Date Mar. 31, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period true  
Entity Common Stock, Shares Outstanding   41,272,308