Leases - Narrative (Details) $ in Millions	12 Months Ended
	Sep. 30, 2023 USD ($) ft² option	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 25, 2023 USD ($)	Dec. 23, 2022	Nov. 19, 2021 USD ($) ft² option
Lessee Lease Description [Line Items]
Short-term lease cost | $	$ 1.4	$ 0.3	$ 0.0
Research Facility in San Diego | California
Lessee Lease Description [Line Items]
Lease term						15 years
Office space leases (in sq ft) | ft²						144,000
Operating lease renewal term						10 years
Maximum additional tenant improvement allowance | $				$ 23.6		$ 7.2
Interest per annum				9.00%		7.00%
Additional tenant improvement allowance liability | $	$ 27.8
Research Facility in San Diego | California | Sorrento Valley Owner (DE) LLC
Lessee Lease Description [Line Items]
Lease term					6 months
Research Facility in San Diego | California | Maximum
Lessee Lease Description [Line Items]
Number of options to renew | option						1
Corporate Headquarters In Pasadena | California
Lessee Lease Description [Line Items]
Office space leases (in sq ft) | ft²	49,000
Corporate Headquarters In Pasadena | California | Colorado Owner, LLC
Lessee Lease Description [Line Items]
Number of options to renew | option	1
Operating lease renewal term	5 years
Research Facility in Madison | Wisconsin
Lessee Lease Description [Line Items]
Office space leases (in sq ft) | ft²	115,000
Number of options to renew | option	2
Operating lease renewal term	5 years