Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Nov. 09, 2023
Cover [Abstract]
Entity Registrant Name	CYCLERION THERAPEUTICS, INC.
Document Type	10-Q
Document Period End Date	Sep. 30, 2023
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		2,445,096
Entity Central Index Key	0001755237
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Entity Tax Identification Number	83-1895370
Entity File Number	001-38787
Entity Incorporation, State or Country Code	MA
Entity Address, Address Line One	245 First Street
Entity Address, Address Line Two	18th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	857
Local Phone Number	327-8778
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	CYCN
Security Exchange Name	NASDAQ