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Related Party Transactions - Narrative (Details)				3 Months Ended
Related Party Transactions - Narrative (Details)	Dec. 14, 2023 USD ($)	Nov. 22, 2023 $ / shares shares	Jul. 12, 2023 USD ($)	Mar. 31, 2024 USD ($) seat shares	Mar. 31, 2023 USD ($) shares	Dec. 31, 2023 USD ($)	Jul. 31, 2023 USD ($)
Related Party Transaction [Line Items]
Stock-based compensation				$ 13,835,000	$ 1,709,000
Related party accounts payable and other current liabilities				$ 15,528,000		$ 16,584,000
Options granted (in shares) \| shares				1,044,658	177,620
Stock-based compensation expense				$ 13,835,000	$ 1,709,000
Paragon Agreement
Related Party Transaction [Line Items]
Number of board seats held by related party \| seat				2
Related Party
Related Party Transaction [Line Items]
Related party accounts payable and other current liabilities				$ 15,500,000		16,600,000
Related Party \| Paragon Agreement
Related Party Transaction [Line Items]
Amount of related party transaction				18,200,000
Stock-based compensation				5,400,000
Related party accounts payable and other current liabilities				$ 10,100,000		$ 16,600,000
Common stock, shares outstanding, percentage available to purchase on a diluted basis				1.00%
Related Party \| Subsequent to Asset Acquisition
Related Party Transaction [Line Items]
Amount of related party transaction				$ 17,100,000
Related Party \| SPY001 License Agreement
Related Party Transaction [Line Items]
Nomination fee			$ 1,500,000
First milestone payment			$ 2,500,000
Related Party \| SPY002 License Agreement
Related Party Transaction [Line Items]
Nomination fee	$ 1,500,000
First milestone payment	$ 2,500,000
Sublicensing fee, maximum amount				20,000,000.0
Related Party \| Consulting Agreement
Related Party Transaction [Line Items]
Options granted (in shares) \| shares		477,000
Exercise price (in dollars per share) \| $ / shares		$ 10.39
Vesting period		36 months
Stock-based compensation expense				$ 300,000	$ 0
Related Party \| Consulting Agreement \| Share-Based Payment Arrangement, Tranche One
Related Party Transaction [Line Items]
Vesting percentage		25.00%
Vesting period		1 year
Paragon Therapeutics Inc \| Maximum \| Related Party \| Paragon Agreement
Related Party Transaction [Line Items]
Percentage of ownership by noncontrolling owner				5.00%
Paragon Therapeutics Inc \| Maximum \| Related Party \| SPY001 License Agreement
Related Party Transaction [Line Items]
Contingent obligation based on milestones							$ 22,000,000.0
Fairmount Funds Management LLC \| Minimum \| Related Party \| Paragon Agreement
Related Party Transaction [Line Items]
Percentage of ownership by noncontrolling owner				5.00%
Percentage of ownership held in third party				5.00%