Segment and Geographic Information - Schedule of Long-lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Sep. 30, 2025
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Total long-lived assets, net	$ 233,848	$ 208,002
United States
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Total long-lived assets, net	113,695	116,681
China
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Total long-lived assets, net	59,301	56,715
United Kingdom
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Total long-lived assets, net	43,122	14,338
Rest of Europe
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Total long-lived assets, net	14,676	16,674
Asia Pacific (Excluding China)
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Total long-lived assets, net	2,885	3,505
Other
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Total long-lived assets, net	$ 169	$ 89