Collaboration and License Agreements - Takeda Pharmaceuticals U.S.A., Inc - Additional Information (Detail) $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 07, 2020 USD ($) bundle obligation	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jan. 31, 2021 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues		$ 32,412	$ 45,891	$ 211,656	$ 100,004
Deferred revenue		84,288		84,288		$ 111,055
Deferred revenue, net of current portion		71,162		71,162		$ 131,495
Takeda License Agreement | License and Co-Funding Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Cash received as due under collaboration agreement							$ 300,000
Number of distinct performance obligations | obligation	1
Number of distinct bundle | bundle	1
Initial transaction price	$ 300,000
Revenues		25,500	$ 35,700	67,100	$ 69,300
Contract assets		0		0
Takeda License Agreement | License and Co-Funding Agreement | Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue		71,000		71,000
Deferred revenue, net of current portion		71,200		71,200
Takeda License Agreement | License and Co-Funding Agreement | Accrued Expenses
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue		$ 7,800		$ 7,800
Takeda License Agreement | License and Co-Funding Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of eligible to receive tiered royalties on net sales	20.00%
Takeda License Agreement | License and Co-Funding Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of eligible to receive tiered royalties on net sales	25.00%
Development regulatory and sales milestones payments							$ 740,000