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Collaboration and License Agreements - Janssen Pharmaceuticals, Inc. (Details)		12 Months Ended
	Oct. 03, 2018 USD ($) obligation	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	May 31, 2021 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from the issuance of common stock		$ 0	$ 0	$ 250,479,000
Deferred revenue		74,099,000	111,055,000
Revenues		243,231,000	138,287,000	$ 87,992,000
Collaboration and License agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Initial transaction price	$ 252,700,000
Janssen \| Collaboration and License agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Cash received as due under collaboration agreement	175,000,000
JJDC \| Common Stock Purchase Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from the issuance of common stock	75,000,000
Janssen
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment	73,000,000
Development, regulatory and sales milestones payments		4,900,000,000
Janssen \| License Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development, regulatory and sales milestones payments	1,600,000,000
Janssen \| Collaboration Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development, regulatory and sales milestones payments	600,000,000
Janssen \| J N J3989 A R O H B V Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment	$ 25,000,000
Number of distinct performance obligations \| obligation	1
Contract assets		0
Deferred revenue		0
Janssen \| JNJ-75220795 (ARO-JNJ1)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment			10,000,000		$ 10,000,000
Contract assets		100,000
Deferred revenue		0
Revenues		$ 3,400,000	$ 500,000