Statements of Stockholders Equity - USD ($) $ in Thousands	Total	2023 ESPP [Member]	May 2025 Private Placement [Member]	October 2025 Financing Transactions [Member]	Common Stock [Member]	Common Stock [Member] 2023 ESPP [Member]	Common Stock [Member] May 2025 Private Placement [Member]	Common Stock [Member] October 2025 Financing Transactions [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] 2023 ESPP [Member]	Additional Paid-in Capital [Member] May 2025 Private Placement [Member]	Additional Paid-in Capital [Member] October 2025 Financing Transactions [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Balance, shares at Dec. 31, 2023					26,646,378
Balance, value at Dec. 31, 2023	$ 113,535				$ 3					$ 295,372					$ (181,840)
Exercise of stock options, shares					135,646
Exercise of stock options, value	491									491
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, Shares					14,159
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, Value	59									59
Issuance of common stock, Shares					6,278,905
Issuance of common stock, Value	88,712									88,712
Additional issuance costs incurred related to issuance of convertible SAFE Note, Shares					(3,827)
Additional issuance costs incurred related to issuance of convertible SAFE Note, Value	24									24
Treasury stock repurchases, Value	(17)								$ (17)
Unrealized comprehensive gain (loss) on investments in U.S. Treasury securities	(103)													$ (103)
Stock-based compensation expense	12,474									12,474
Net loss	(98,333)														(98,333)
Balance, shares at Dec. 31, 2024					33,071,261
Balance, value at Dec. 31, 2024	116,842				$ 3				(17)	397,132				(103)	(280,173)
Exercise of stock options, shares					15,300
Exercise of stock options, value	59									59
Issuance of common stock upon vesting and settlement of restricted stock units, shares					101,448
Issuance of common stock upon vesting and settlement of performance restricted stock units, shares					76,800
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, Shares					7,532
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, Value	37									37
Issuance of common stock, Shares						102,837	20,790,120	17,968,750
Issuance of common stock, Value		$ 270	$ 73,082	$ 143,917			$ 2	$ 2			$ 270	$ 73,080	$ 143,915
Issuance of common stock upon exercise of pre-funded warrants, shares					867,302
Unrealized comprehensive gain (loss) on investments in U.S. Treasury securities	291													291
Stock-based compensation expense	12,132									12,132
Net loss	(99,961)														(99,961)
Balance, shares at Dec. 31, 2025					73,001,350
Balance, value at Dec. 31, 2025	$ 246,669				$ 7				$ (17)	$ 626,625				$ 188	$ (380,134)

Lexeo Therapeutics, Inc. 10-K