Organization and Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Nov. 09, 2022	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2023	Sep. 30, 2022
Organization And Significant Accounting Policies [Line Items]
Cash, cash equivalents and restricted cash		$ 105,300		$ 105,300
Restricted cash		7,300		7,300
Short term investments		346,369		346,369	$ 268,391
Long-term investments		42,758		42,758	$ 105,872
Increase in cash and investments				12,200
Development regulatory and sales milestones payments		3,400,000		3,400,000
Horizon and Amgen
Organization And Significant Accounting Policies [Line Items]
Upfront milestone payment received				110,000
Takeda | License and Co-Funding Agreement
Organization And Significant Accounting Policies [Line Items]
Milestone payment receivable		40,000		40,000
GSK | Collaboration and License agreements
Organization And Significant Accounting Policies [Line Items]
Milestone payment receivable		30,000		30,000
Horizon
Organization And Significant Accounting Policies [Line Items]
Upfront milestone payment received		$ 15,000	$ 15,000
Amgen
Organization And Significant Accounting Policies [Line Items]
Upfront milestone payment received			$ 25,000
Royalty Pharma
Organization And Significant Accounting Policies [Line Items]
Upfront milestone payment received	$ 250,000			$ 250,000