XML 16 R1.htm IDEA: XBRL DOCUMENT v3.22.1
Document and Entity Information - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2021
Mar. 25, 2022
Jun. 30, 2021
Cover [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2021    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Title of 12(b) Security Common Stock, $0.001 par value per share    
Trading Symbol SPRO    
Security Exchange Name NASDAQ    
Entity Registrant Name SPERO THERAPEUTICS, INC.    
Entity Central Index Key 0001701108    
Current Fiscal Year End Date --12-31    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company true    
Entity Ex Transition Period true    
Entity Common Stock, Shares Outstanding   32,755,559  
Entity Public Float     $ 326.3
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Shell Company false    
Entity File Number 001-38266    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 46-4590683    
Entity Address, Address Line One 675 Massachusetts Avenue,    
Entity Address, Address Line Two 14th Floor    
Entity Address, City or Town Cambridge    
Entity Address, State or Province MA    
Entity Address, Postal Zip Code 02139    
City Area Code 857    
Local Phone Number 242-1600    
Document Annual Report true    
Document Transition Report false    
ICFR Auditor Attestation Flag false    
Documents Incorporated by Reference

DOCUMENTS INCORPORATED BY REFERENCE

None.

   
Auditor Name PricewaterhouseCoopers LLP    
Auditor Location Boston, Massachusetts    
Auditor Firm ID 238