Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Jan. 31, 2025	Jun. 28, 2024
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2024
Document Transition Report	false
Securities Act 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 Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 76.1
Entity Common Stock, Shares Outstanding		107,918,821
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Philadelphia, Pennsylvania
Entity Central Index Key	0001557746
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false