v3.26.1
Document and Entity Information - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2025
Mar. 31, 2026
Jun. 30, 2025
Document Type 10-K/A    
Amendment Flag true    
Document Period End Date Dec. 31, 2025    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Entity Registrant Name SYNLOGIC, INC.    
Entity Central Index Key 0001527599    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
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 [Flag] false    
Entity Shell Company true    
Entity Common Stock, Shares Outstanding   11,698,919  
Entity Public Float     $ 4.4
Entity File Number 001-37566    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 26-1824804    
Entity Interactive Data Current Yes    
Entity Address, Address Line One PO Box    
Entity Address, Address Line Two 30    
Entity Address, City or Town Winchester    
Entity Address, State or Province MA    
Entity Address, Postal Zip Code 01890    
City Area Code 617    
Local Phone Number 659-2802    
Document Annual Report true    
Document Transition Report false    
Auditor Firm ID 185    
Auditor Name KPMG LLP    
Auditor Location Boston, MA    
Amendment Description This registrant is filing this Amendment No. 1 (“Amendment”) to its Annual Report on Form 10-K for the year ended December 31, 2025 as filed with the Securities and Exchange Commission (the “SEC”) on March 12, 2026 (the “Original Filing”) solely to include the information required by Item 10 - “Directors, Executive Officers and Corporate Governance,” Item 11 - “Executive Compensation,” Item 12 - “Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters,” Item 13 - “Certain Relationships and Related Transactions, and Director Independence” and Item 14 - “Principal Accounting Fees and Services” of Part III of Form 10-K that was intentionally omitted from Part III of Original Filing. The reference on the cover page of the Original Filing to the incorporation by reference of portions of our definitive proxy statement into Part III of the Original Filing is hereby deleted. Items 10, 11, 12, 13 and 14 of Part III of the Original Filing are amended and restated in their entirety as set forth in this Amendment. In addition, pursuant to Rule 13a-14(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), we are including with this Amendment certain currently dated certifications. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of the certifications have been omitted. We are not including the certifications under Section 906 of the Sarbanes-Oxley Act of 2002 as no financial statements are being filed with this Amendment. Except as described above, no other amendments are being made to the Original Filing. This Amendment does not reflect events occurring after the March 12, 2026 filing of the Original Filing or modify or update the disclosure contained in the Original Filing in any way other than as required to reflect the amendments discussed above and reflected below. Accordingly, this Amendment should be read in conjunction with the Original Filing and our other filings with the SEC. Terms used but not defined herein shall have the meanings ascribed to them in the Original Filing.    
Documents Incorporated by Reference

DOCUMENTS INCORPORATED BY REFERENCE

None.