Cover - USD ($)	12 Months Ended
	Dec. 31, 2023	Apr. 09, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K/A
Amendment Flag	true
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Trading Symbol	TCRX
Entity Registrant Name	TScan Therapeutics, Inc.
Entity Central Index Key	0001783328
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Document Annual Report	true
Document Transition Report	false
Entity File Number	001-40603
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-5282075
Entity Address, Address Line One	830 Winter Street
Entity Address, State or Province	MA
Entity Address, City or Town	Waltham
Entity Address, Postal Zip Code	02451
City Area Code	857
Local Phone Number	399-9500
Title of 12(b) Security	Voting Common Stock, $0.0001 par value per share
Document Financial Statement Error Correction [Flag]	false
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	false
Entity Public Float			$ 74,489,510
Documents Incorporated by Reference [Text Block]	None
Amendment Description	TScan Therapeutics, Inc. is filing this Amendment No. 1 on Form 10-K/A, or this Amendment No. 1 to our Annual Report on Form 10-K for the fiscal year ended December 31, 2023, or the Original 10-K, originally filed with the U.S. Securities and Exchange Commission, or SEC, on March 6, 2024, or Original Filing Date, solely for the purpose of including the information required by Items 10 through 14 of Part III of Form 10-K. This information was previously omitted from the Original 10-K in reliance on General Instruction G(3) to Form 10-K, which permits the information in the above referenced items to be incorporated in the Original 10-K by reference from our definitive proxy statement so long as such proxy statement is filed no later than 120 days after our fiscal year-end. We are filing this Amendment No. 1 to include the Part III information in the Original Form 10-K because we will not file a definitive proxy statement containing such information within 120 days after the end of the fiscal year covered by the Original 10-K. This Amendment No. 1 amends and restates in their entirety Items 10 through 14 of the Original 10-K. Pursuant to Rule 12b-15 under the Securities Exchange Act of 1934, as amended, or the Exchange Act, this Amendment No. 1 also contains new certifications by the principal executive officer and the principal financial officer as required by Section 302 of the Sarbanes-Oxley Act of 2002. Accordingly, Item 15 of Part IV is amended to include the currently dated certifications of our principal executive officer and principal financial officer as exhibits. Because no financial statements have been included in this Amendment No. 1 and this Amendment No. 1 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. In addition, because no financial statements are included in this Amendment No. 1, new certifications of our principal executive officer and principal financial officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 are not required to be included with Amendment No. 1. Except as described above, no other changes have been made to the Original 10-K. The Original 10-K continues to speak as of the date of the Original 10-K, and we have not updated the disclosures contained therein to reflect any events that have occurred as of a date subsequent to the date of the Original 10-K. Accordingly, this Amendment No. 1 should be read in conjunction with the Original 10-K. Defined terms used, but not defined, herein have the meanings ascribed to them in the Original 10-K. Unless stated otherwise, references in this Amendment No. 1 to “us,” “we,” “our,” “our Company,” “the Company,” or “TScan” and similar terms refer to TScan Therapeutics, Inc.
Voting Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		43,628,149
Non-voting Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		4,276,588