Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Feb. 28, 2021
Jun. 30, 2020
Cover [Abstract]      
Entity Registrant Name SYROS PHARMACEUTICALS, INC.    
Trading Symbol SYRS    
Entity Central Index Key 0001556263    
Document Type 10-K    
Document Period End Date Dec. 31, 2020    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Non-accelerated Filer    
Entity Common Stock, Shares Outstanding   61,639,252  
Entity Public Float     $ 442,688,853
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Entity Small Business true    
Entity Ex Transition Period true    
Entity Emerging Growth Company true    
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 Annual 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    
ICFR Auditor Attestation Flag false