Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 808
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479402/808-10-50-1

Collaboration and License Agreements - Collaboration and License Agreement with Astellas US LLC (Details) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended	9 Months Ended
	Apr. 15, 2026 USD ($) $ / shares shares	Jun. 30, 2026 USD ($)	Sep. 30, 2026 USD ($)	Sep. 30, 2026 USD ($)	Sep. 09, 2024
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Global development costs shared (as a percent)	40.00%
Sanofi Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Asset acquisition, milestone payment		$ 48.0
Percentage of income eligible to receive					0.20
Astellas
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments	$ 240.0
Sale of stock (in shares) \| shares	7,239,382
Issuance of common stock related to a follow-on public offering, net of issuance costs	$ 75.0
Net proceeds received	$ 75.7
Sale of stock (in USD per share) \| $ / shares	$ 10.46
Discount on shares	$ 0.7
Global development costs shared (as a percent)	60.00%
Maximum future development, regulatory and ex-US sales milestone payments	$ 1,390.0
Maximum future development, regulatory and sales milestones payments	1,390.0
Potential additional future development, regulatory and sales milestone payments, maximum	1,620.0
Astellas \| License and collaboration revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Net upfront payment	$ 239.3
Astellas \| VIR‑5500 Program License
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Credit to research and development			$ 8.6	$ 13.6
Astellas \| Astellas Agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Credit to prepaid expenses and other current assets			$ 8.6	$ 8.6