Balance sheet components - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 180,539	$ 171,218
Less: Accumulated depreciation and amortization	(35,689)	(31,777)
Property and equipment, net	144,850	139,441
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	65,393	62,285
Furniture, fixtures and other equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,487	2,332
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,867	2,814
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,693	1,693
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	58,876	14,371
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 49,223	$ 87,723