Condensed Consolidated Statements of Changes in Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Series A Non Voting Convertible Preferred Stock	Series B Non Voting Convertible Preferred Stock	Preferred Stock Series A Non Voting Convertible Preferred Stock	Preferred Stock Series B Non Voting Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2022				0
Beginning balance at Dec. 31, 2022				$ 0
Ending balance (in shares) at Mar. 31, 2023				0
Ending balance at Mar. 31, 2023				$ 0
Beginning balance, common stock (in shares) at Dec. 31, 2022						2,614,000
Beginning balance at Dec. 31, 2022	$ 50,305					$ 6	$ 475,971	$ (48)	$ (425,624)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with employee stock purchase plan (in shares)						2,000
Issuance of common stock in connection with employee stock purchase plan	18						18
Stock-based compensation expense	1,709						1,709
Foreign currency translation adjustment	10							10
Unrealized gain (loss) on marketable securities	32							32
Net loss	(18,422)								(18,422)
Ending balance, common stock (in shares) at Mar. 31, 2023						2,616,000
Ending balance at Mar. 31, 2023	33,652					$ 6	477,698	(6)	(444,046)
Beginning balance (in shares) at Dec. 31, 2022				0
Beginning balance at Dec. 31, 2022				$ 0
Ending balance (in shares) at Sep. 30, 2023				1,086,000
Ending balance at Sep. 30, 2023				$ 387,105
Beginning balance, common stock (in shares) at Dec. 31, 2022						2,614,000
Beginning balance at Dec. 31, 2022	50,305					$ 6	475,971	(48)	(425,624)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	(1)
Unrealized gain (loss) on marketable securities	(83)
Net loss	(275,610)
Ending balance, common stock (in shares) at Sep. 30, 2023						4,049,000
Ending balance at Sep. 30, 2023	(245,402)					$ 7	455,957	(132)	(701,234)
Beginning balance (in shares) at Mar. 31, 2023				0
Beginning balance at Mar. 31, 2023				$ 0
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series A/B non-voting convertible preferred stock in connection with private placement, net of financing costs (in shares)				721,000
Issuance of Series A/B non-voting convertible preferred stock in connection with private placement, net of financing costs				$ 197,323
Ending balance (in shares) at Jun. 30, 2023				721,000
Ending balance at Jun. 30, 2023				$ 197,323
Beginning balance, common stock (in shares) at Mar. 31, 2023						2,616,000
Beginning balance at Mar. 31, 2023	33,652					$ 6	477,698	(6)	(444,046)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock forward in connection with the asset acquisition of Spyre	3,768						3,768
Issuance of common stock in connection with exercise of pre-funded warrants (in shares)						624,000
CVR distribution to common stockholders	(29,500)						(29,500)
Stock-based compensation expense	1,775						1,775
Foreign currency translation adjustment	18							18
Unrealized gain (loss) on marketable securities	(1)							(1)
Net loss	(217,081)								(217,081)
Ending balance, common stock (in shares) at Jun. 30, 2023						3,240,000
Ending balance at Jun. 30, 2023	(207,369)					$ 6	453,741	11	(661,127)
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series A non-voting convertible preferred stock in connection with the asset acquisition of Spyre and settlement of related forward contract (in shares)				365,000
Issuance of Series A non-voting convertible preferred stock in connection with the asset acquisition of Spyre and settlement of related forward contract				$ 189,741
Settlement of financing costs in connection with private placement of Series A non-voting convertible preferred stock				$ 41
Ending balance (in shares) at Sep. 30, 2023				1,086,000
Ending balance at Sep. 30, 2023				$ 387,105
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with exercise of stock options and employee stock purchase plan (in shares)						10,000
Issuance of common stock in connection with exercise of stock options and employee stock purchase plan	105						105
Issuance of common stock in connection with exercise of pre-funded warrants (in shares)						281,000
Issuance of common stock in connection with the asset acquisition of Spyre and settlement of related forward contract (in shares)						518,000
Issuance of common stock in connection with the asset acquisition of Spyre and settlement of related forward contract	0					$ 1	(1)
Stock-based compensation expense	2,112						2,112
Foreign currency translation adjustment	(29)							(29)
Unrealized gain (loss) on marketable securities	(114)							(114)
Net loss	(40,107)								(40,107)
Ending balance, common stock (in shares) at Sep. 30, 2023						4,049,000
Ending balance at Sep. 30, 2023	(245,402)					$ 7	455,957	(132)	(701,234)
Beginning balance (in shares) at Dec. 31, 2023			150,000		150,000
Beginning balance at Dec. 31, 2023			$ 84,555		$ 84,555
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series A/B non-voting convertible preferred stock in connection with private placement, net of financing costs (in shares)					122,000
Issuance of Series A/B non-voting convertible preferred stock in connection with private placement, net of financing costs					$ 168,850
Ending balance (in shares) at Mar. 31, 2024					272,000
Ending balance at Mar. 31, 2024					$ 253,405
Beginning balance, preferred stock (in shares) at Dec. 31, 2023		437,037		437,000	0
Beginning balance, common stock (in shares) at Dec. 31, 2023						36,057,000
Beginning balance at Dec. 31, 2023	184,016			$ 184,927	$ 0	$ 10	763,191	302	(764,414)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with exercise of stock options and employee stock purchase plan (in shares)						572,000
Issuance of common stock in connection with exercise of stock options and employee stock purchase plan	4,390						4,390
Stock-based compensation expense	8,385						8,385
Foreign currency translation adjustment	16							16
Unrealized gain (loss) on marketable securities	(681)							(681)
Net loss	(43,857)								(43,857)
Ending balance, preferred stock (in shares) at Mar. 31, 2024				437,000	0
Ending balance, common stock (in shares) at Mar. 31, 2024						36,629,000
Ending balance at Mar. 31, 2024	152,269			$ 184,927	$ 0	$ 10	775,966	(363)	(808,271)
Beginning balance (in shares) at Dec. 31, 2023			150,000		150,000
Beginning balance at Dec. 31, 2023			$ 84,555		$ 84,555
Ending balance (in shares) at Sep. 30, 2024					0
Ending balance at Sep. 30, 2024			$ 0		$ 0
Beginning balance, preferred stock (in shares) at Dec. 31, 2023		437,037		437,000	0
Beginning balance, common stock (in shares) at Dec. 31, 2023						36,057,000
Beginning balance at Dec. 31, 2023	184,016			$ 184,927	$ 0	$ 10	763,191	302	(764,414)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	37
Unrealized gain (loss) on marketable securities	1,118
Net loss	(151,722)
Ending balance, preferred stock (in shares) at Sep. 30, 2024		346,045	16,667	346,000	17,000
Ending balance, common stock (in shares) at Sep. 30, 2024						51,396,000
Ending balance at Sep. 30, 2024	327,390			$ 146,425	$ 9,395	$ 12	1,086,237	1,457	(916,136)
Beginning balance (in shares) at Mar. 31, 2024					272,000
Beginning balance at Mar. 31, 2024					$ 253,405
Increase (Decrease) in Temporary Equity [Roll Forward]
Stockholder approval of the issuance of Common Stock upon conversion of Series B convertible non-voting preferred stock (in shares)					(272,000)
Stockholder approval of the issuance of Common Stock upon conversion of Series B convertible non-voting preferred stock					$ (253,405)
Ending balance (in shares) at Jun. 30, 2024					0
Ending balance at Jun. 30, 2024					$ 0
Beginning balance, preferred stock (in shares) at Mar. 31, 2024				437,000	0
Beginning balance, common stock (in shares) at Mar. 31, 2024						36,629,000
Beginning balance at Mar. 31, 2024	152,269			$ 184,927	$ 0	$ 10	775,966	(363)	(808,271)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholder approval of conversion of Series B Convertible Non-Voting Preferred Stock to Common Stock (in shares)					272,000
Stockholder approval of the issuance of Common Stock upon conversion of Series B convertible non-voting preferred stock	253,405				$ 253,405
Issuance of common stock in connection with exercise of stock options and employee stock purchase plan (in shares)						66,000
Issuance of common stock in connection with exercise of stock options and employee stock purchase plan	494						494
Conversion of Series B non-voting convertible preferred stock into common stock (in shares)					(255,000)	10,198,000
Conversion of Series B non-voting convertible preferred stock into common stock	0				$ (244,010)	$ 1	244,009
Exchange of Series A non-voting convertible preferred stock into common stock (in shares)				(91,000)		3,640,000
Exchange of Series A non-voting convertible preferred stock for common stock	0			$ (38,502)		$ 1	38,501
Issuance of common stock in connection with exercise of pre-funded warrants (in shares)						250,000
Issuance of common stock in connection with exercise of pre-funded warrants	1						1
Stock-based compensation expense	7,243						7,243
Foreign currency translation adjustment	4							4
Unrealized gain (loss) on marketable securities	(194)							(194)
Net loss	(38,837)								(38,837)
Ending balance, preferred stock (in shares) at Jun. 30, 2024				346,000	17,000
Ending balance, common stock (in shares) at Jun. 30, 2024						50,783,000
Ending balance at Jun. 30, 2024	374,385			$ 146,425	$ 9,395	$ 12	1,066,214	(553)	(847,108)
Ending balance (in shares) at Sep. 30, 2024					0
Ending balance at Sep. 30, 2024			$ 0		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with exercise of stock options and employee stock purchase plan (in shares)						153,000
Issuance of common stock in connection with exercise of stock options and employee stock purchase plan	1,318						1,318
Issuance of common stock in connection with at-the-market offerings, net of offering costs (in shares)						426,000
Issuance of common stock in connection with at-the-market offerings, net of offering costs	11,750						11,750
Vesting of restricted stock units (in shares)						34,000
Stock-based compensation expense	6,955						6,955
Foreign currency translation adjustment	17							17
Unrealized gain (loss) on marketable securities	1,993							1,993
Net loss	(69,028)								(69,028)
Ending balance, preferred stock (in shares) at Sep. 30, 2024		346,045	16,667	346,000	17,000
Ending balance, common stock (in shares) at Sep. 30, 2024						51,396,000
Ending balance at Sep. 30, 2024	$ 327,390			$ 146,425	$ 9,395	$ 12	$ 1,086,237	$ 1,457	$ (916,136)