Collaboration Agreements - Summary of Collaboration Revenue (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenue, revenue from contract with customer	[1]	$ 0	$ 35,141
Total Collaboration Revenue		0	35,141
Takeda Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total Collaboration Revenue		0	10,000
Takeda Collaboration Agreement | PTV:PGRN Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenue, revenue from contract with customer		0	10,000
Sanofi Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total Collaboration Revenue		0	25,000
Sanofi Collaboration Agreement | CNS Program License
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenue, revenue from contract with customer		0	25,000
Biogen
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total Collaboration Revenue		0	141
Biogen | Option Research Services
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenue, revenue from contract with customer		$ 0	$ 141

[1] Includes related-party collaboration revenue from customers of $0.1 million for the three months ended March 31, 2023.