Stock-based compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	$ 10,598	$ 19,859	$ 18,531	$ 60,263
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	1,286	1,228	3,898	3,347
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	3,329	5,642	10,837	14,506
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	$ 5,983	$ 12,989	$ 3,796	$ 42,410