Collaboration and License Agreements - Joint Venture and License Agreement with Visirna Therapeutics, Inc. (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Apr. 25, 2022	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from investment in joint venture				$ 0	$ 60,000
Revenue		$ 15,825	$ 32,412	224,638	$ 211,656
Deferred revenue		16,905		16,905		$ 74,099
Visirna Therapeutics, Inc. | Visirna License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue				900
Contract assets		0		0
Deferred revenue		$ 0		$ 0
Visirna Therapeutics, Inc. | Visirna License Agreement | Variable Interest Entity, Primary Beneficiary
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from investment in joint venture	$ 60,000