Merger with Sesen Bio - Schedule of Net Assets Acquired in the Merger (Details) $ in Thousands	10 Months Ended
	Dec. 31, 2023 USD ($) seat shares	Mar. 07, 2023 USD ($) shares	Dec. 31, 2022 shares
Merger with Sesen Bio
Number of board seats | seat	7
Entity common stock, shares outstanding immediately after merger | shares	40,609,915		2,217,737
Cash and cash equivalents		$ 37,873
Marketable securities		44,588
Prepaid expenses and other assets		1,316
Restricted cash		30
Accounts payable and accrued expenses		(3,499)
Total net assets acquired		80,308
Less: Transaction costs		(8,264)
Total net assets acquired less transaction costs		$ 72,044
Carisma Therapeutics Inc.
Merger with Sesen Bio
Severance and personnel costs paid	$ 4,600
CARISMA Therapeutics Inc, Legacy, Stockholders | Carisma Therapeutics Inc.
Merger with Sesen Bio
Business acquisition percentage of voting interests acquired		74.20%
Entity common stock, shares outstanding immediately after merger | shares		40,254,666