Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance at Dec. 31, 2023	$ (45,017)			$ 2,377		$ (47,394)
Balance, Shares at Dec. 31, 2023			1,362,481
Temporary Equity Balance at Dec. 31, 2023		$ 44,408
Temporary Equity Balance, Shares at Dec. 31, 2023		41,871,340
Issuance of Series B-2 redeemable convertible preferred stock		$ 1,591
Issuance of Series B-2 redeemable convertible preferred stock, Shares		1,280,000
Capital contributions - in-kind services - related party	60			60
Premium on issuance of convertible promissory notes	793			793
Stock-based compensation expense	31			31
Net loss	(3,407)					(3,407)
Balance at Mar. 31, 2024	(47,540)			3,261		(50,801)
Balance, Shares at Mar. 31, 2024			1,362,481
Temporary Equity Balance at Mar. 31, 2024		$ 45,999
Temporary Equity Balance, Shares at Mar. 31, 2024		43,151,340
Balance at Dec. 31, 2023	(45,017)			2,377		(47,394)
Balance, Shares at Dec. 31, 2023			1,362,481
Temporary Equity Balance at Dec. 31, 2023		$ 44,408
Temporary Equity Balance, Shares at Dec. 31, 2023		41,871,340
Unrealized gain on available-for-sale securities, net of tax	0
Net loss	(47,141)
Balance at Sep. 30, 2024	(89,380)			5,155		(94,535)
Balance, Shares at Sep. 30, 2024			1,353,072
Temporary Equity Balance at Sep. 30, 2024		$ 45,999
Temporary Equity Balance, Shares at Sep. 30, 2024		43,151,340
Balance at Mar. 31, 2024	(47,540)			3,261		(50,801)
Balance, Shares at Mar. 31, 2024			1,362,481
Temporary Equity Balance at Mar. 31, 2024		$ 45,999
Temporary Equity Balance, Shares at Mar. 31, 2024		43,151,340
Premium on issuance of convertible promissory notes	1,341			1,341
Stock-based compensation expense	322			322
Net loss	(5,650)					(5,650)
Balance at Jun. 30, 2024	(51,527)			4,924		(56,451)
Balance, Shares at Jun. 30, 2024			1,362,481
Temporary Equity Balance at Jun. 30, 2024		$ 45,999
Temporary Equity Balance, Shares at Jun. 30, 2024		43,151,340
Stock-based compensation expense	262			262
Issuance of common stock upon stock option exercises	1			1
Issuance of common stock upon stock option exercises, Shares			671
Repurchase of common stock in connection with the royalty agreement	(32)			(32)
Repurchase of common stock in connection with the royalty agreement, Shares			(10,080)
Unrealized gain on available-for-sale securities, net of tax	0
Net loss	(38,084)					(38,084)
Balance at Sep. 30, 2024	(89,380)			5,155		(94,535)
Balance, Shares at Sep. 30, 2024			1,353,072
Temporary Equity Balance at Sep. 30, 2024		$ 45,999
Temporary Equity Balance, Shares at Sep. 30, 2024		43,151,340
Balance at Dec. 31, 2024	(96,616)			19,945		(116,561)
Balance, Shares at Dec. 31, 2024			1,356,431
Temporary Equity Balance at Dec. 31, 2024	$ 45,999	$ 45,999
Temporary Equity Balance, Shares at Dec. 31, 2024	43,151,340	43,151,340
Premium on issuance of convertible promissory notes	$ 186			186
Issuance of Series B-2 redeemable convertible preferred stock upon conversion of convertible promissory notes in connection with the Merger		$ 3,695
Issuance of Series B-2 redeemable convertible preferred stock upon conversion of convertible promissory notes in connection with the Merger, Shares		794,499
Conversion of convertible promissory notes into common stock in connection with the Merger	20,799			20,799
Conversion of convertible promissory notes into common stock in connection with the Merger, Shares			3,418,839
Conversion of redeemable convertible preferred stock into common stock in connection with the Merger		$ (49,694)
Conversion of redeemable convertible preferred stock into common stock in connection with the Merger, Shares		(43,945,839)
Conversion of redeemable convertible preferred stock into common stock in connection with the Merger	49,694		$ 1	49,693
Conversion of redeemable convertible preferred stock into common stock in connection with the Merger, Shares			8,859,474
Recognition of AlloVir common stock outstanding at the closing of the Merger	104,990		$ 1	104,989
Recognition of AlloVir common stock outstanding at the closing of the Merger, Shares			5,067,674
Transaction costs related to the Merger	(5,357)			(5,357)
Stock-based compensation expense	374			374
Net loss	(10,196)					(10,196)
Balance at Mar. 31, 2025	63,874		$ 2	190,629		(126,757)
Balance, Shares at Mar. 31, 2025			18,702,418
Balance at Dec. 31, 2024	(96,616)			19,945		(116,561)
Balance, Shares at Dec. 31, 2024			1,356,431
Temporary Equity Balance at Dec. 31, 2024	$ 45,999	$ 45,999
Temporary Equity Balance, Shares at Dec. 31, 2024	43,151,340	43,151,340
Unrealized gain on available-for-sale securities, net of tax	$ 6
Net loss	(33,440)
Balance at Sep. 30, 2025	41,865		$ 2	191,858	$ 6	(150,001)
Balance, Shares at Sep. 30, 2025			18,702,418
Temporary Equity Balance at Sep. 30, 2025	$ 0
Temporary Equity Balance, Shares at Sep. 30, 2025	0
Balance at Mar. 31, 2025	$ 63,874		$ 2	190,629		(126,757)
Balance, Shares at Mar. 31, 2025			18,702,418
Stock-based compensation expense	591			591
Net loss	(11,350)					(11,350)
Balance at Jun. 30, 2025	53,115		$ 2	191,220		(138,107)
Balance, Shares at Jun. 30, 2025			18,702,418
Stock-based compensation expense	638			638
Unrealized gain on available-for-sale securities, net of tax	6				6
Net loss	(11,894)					(11,894)
Balance at Sep. 30, 2025	41,865		$ 2	$ 191,858	$ 6	$ (150,001)
Balance, Shares at Sep. 30, 2025			18,702,418
Temporary Equity Balance at Sep. 30, 2025	$ 0
Temporary Equity Balance, Shares at Sep. 30, 2025	0