Organization and Significant Accounting Policies - Additional Information (Detail) ft² in Thousands, $ in Thousands		9 Months Ended
	Dec. 20, 2021 ft² a	Jun. 30, 2022 USD ($) ft² a	Nov. 19, 2021 ft²	Sep. 30, 2021 USD ($)
Organization And Significant Accounting Policies [Line Items]
Tax increment financing award		$ 16,000
State income tax credits		2,500
Cash and cash equivalents		139,439		$ 184,434
Restricted cash		7,400
Short term investments		277,057		56,627
Marketable securities		0		126,728
Long term investments		165,920		$ 245,595
Decrease in cash and investments		31,000
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
Variable Interest Entity, Primary Beneficiary | Visirna Therapeutics, Inc.
Organization And Significant Accounting Policies [Line Items]
Cash and cash equivalents		$ 60,000
Wisconsin | Verona Technology Park
Organization And Significant Accounting Policies [Line Items]
Land purchased, number of acres | a	13	13
Wisconsin | Drug Manufacturing Facility
Organization And Significant Accounting Policies [Line Items]
Planned area of the site (in sq ft) | ft²	160	160
Wisconsin | Laboratory and Office Facility
Organization And Significant Accounting Policies [Line Items]
Planned area of the site (in sq ft) | ft²	140	140
California | Research Facility in San Diego
Organization And Significant Accounting Policies [Line Items]
Office space leases (in sq ft) | ft²		144	144