Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Entity Registrant Name	SYROS PHARMACEUTICALS, INC.
Trading Symbol	SYRS
Entity Central Index Key	0001556263
Document Type	10-Q
Document Period End Date	Mar. 31, 2021
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		61,858,267
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Small Business	true
Entity Ex Transition Period	true
Entity Emerging Growth Company	true
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-37813
Entity Tax Identification Number	45-3772460
Entity Address, Address Line One	35 CambridgePark Drive
Entity Address, Address Line Two	4th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02140
City Area Code	617
Local Phone Number	744-1340
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ