Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	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.

SYNLOGIC, INC. 10-K/A