Collaboration and License Agreements - Takeda Pharmaceutical Company Limited (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 07, 2020 USD ($) bundle obligation	Jun. 30, 2023 USD ($) $ / shares	Jun. 30, 2022 USD ($) $ / shares	Jun. 30, 2023 USD ($) $ / shares	Jun. 30, 2022 USD ($) $ / shares	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jan. 31, 2021 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development regulatory and sales milestones payments		$ 3,400,000		$ 3,400,000
Revenues		$ 15,825	$ 32,412	$ 224,638	$ 211,656
Diluted (in dollars per share) | $ / shares		$ (0.96)	$ (0.68)	$ (0.90)	$ (0.86)
Deferred revenue, net of current portion		$ 0		$ 0			$ 55,950
Deferred revenue		16,905		16,905			$ 74,099
Takeda | License and Co-Funding Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Cash received as due under collaboration agreement								$ 300,000
Milestone payment						$ 40,000
Number of distinct performance obligations | obligation	1
Number of distinct bundle | bundle	1
Initial transaction price	$ 300,000
Revenues		$ 61,400		$ 61,400
Diluted (in dollars per share) | $ / shares		$ 0.58		$ 0.58
Milestone payment receivable		$ 40,000		$ 40,000
Takeda | License and Co-Funding Agreement | Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue, net of current portion		16,900		16,900
Deferred revenue		16,900		16,900
Takeda | License and Co-Funding Agreement | Accrued Expenses
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue		1,400		1,400
Takeda | 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 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		$ 527,500		$ 527,500