Segment and Geographic Information - Schedule of Long-lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Sep. 30, 2025
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets, net	$ 231,283	$ 208,002
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets, net	116,187	116,681
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets, net	57,681	56,715
Rest of Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets, net	15,272	16,674
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets, net	38,943	14,338
Asia Pacific (Excluding China)
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets, net	3,146	3,505
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets, net	$ 54	$ 89