Organization and Significant Accounting Policies - Additional Information (Detail) $ in Thousands		6 Months Ended
	Dec. 20, 2021 ft² a	Mar. 31, 2022 USD ($)	Nov. 19, 2021 ft²	Sep. 30, 2021 USD ($)
Organization And Significant Accounting Policies [Line Items]
Cash and cash equivalents		$ 86,408		$ 184,434
Restricted Cash		7,900
Short-term investments		192,912		56,627
Marketable securities		122,600
Long-term investments		201,590		$ 245,595
Net increase (decrease) in cash and investments		9,900
GSK
Organization And Significant Accounting Policies [Line Items]
Upfront milestone payment received		120,000
Janssen
Organization And Significant Accounting Policies [Line Items]
Development regulatory and sales milestones payments		$ 4,900,000
Wisconsin | Drug Manufacturing Facility
Organization And Significant Accounting Policies [Line Items]
Planned area of the site | ft²	140,000
Wisconsin | Laboratory and Office Facility
Organization And Significant Accounting Policies [Line Items]
Planned area of the site | ft²	115,000
Wisconsin | Verona Technology Park
Organization And Significant Accounting Policies [Line Items]
Land purchased, number of acres | a	13
California | Research Facility in San Diego
Organization And Significant Accounting Policies [Line Items]
Office space leases, in square feet | ft²			144,000