Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Jul. 31, 2024
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Document Transition Report	false
Entity File Number	001-37581
Entity Registrant Name	Aclaris Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-0571712
Entity Address, Address Line One	701 Lee Road, Suite 103
Entity Address, City or Town	Wayne
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19087
City Area Code	484
Local Phone Number	324-7933
Title of 12(b) Security	Common Stock, $0.00001 par value
Trading Symbol	ACRS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		71,344,557
Entity Central Index Key	0001557746
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Amendment Flag	false