2023 Restructuring and other costs - Restructuring Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Restructuring Cost and Reserve [Line Items]
Restructuring charges, statement of income or comprehensive income		Restructuring and other costs
Tangible asset impairment charges	$ 9,066	$ 6,785	$ 0
Laboratory equipment
Restructuring Cost and Reserve [Line Items]
Tangible asset impairment charges		3,700
Leasehold improvements
Restructuring Cost and Reserve [Line Items]
Tangible asset impairment charges		1,800
Computer software
Restructuring Cost and Reserve [Line Items]
Tangible asset impairment charges		1,300
2023 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs:		9,384
Impairment of long-lived assets:		16,169
Severance and related benefit costs | 2023 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs:		8,467
Other associated costs | 2023 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs:		917
Asset Impairments | 2023 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs:		$ 6,785