Collaboration and License Agreements - Glaxosmithkline Intellectual Property (No. 3) Limited - Additional Information (Detail) $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 22, 2021 USD ($) obligation bundle	Oct. 03, 2018 USD ($)	Jan. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues				$ 32,412	$ 45,891	$ 211,656	$ 100,004
Contract liabilities				84,288		84,288		$ 111,055
Collaboration and License agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Initial transaction price		$ 252,700
GSK | Collaboration and License agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment	$ 120,000
Milestone payment receivable at start of phase two	30,000
Milestone payment receivable upon achievement of phase two and first patient dosed in phase three	100,000
GSK | Collaboration and License agreements | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Commercial milestone payments at first commercial sale	190,000
Sales-related milestone payments	$ 590,000
GSK | ARO-HSD Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of distinct performance obligations | obligation	1
Number of distinct bundle | bundle	1
Initial transaction price	$ 120,000
Cash received as due under collaboration agreement			$ 120,000
Performance obligation related to agreement, upfront payment				120,000		120,000
Revenues						120,000	$ 0
Contract assets				0		0
Contract liabilities				$ 0		$ 0