Segment and Geographic Information - Reconciliation of Reportable Segment Assets to Corresponding Consolidated Amounts (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Cash and cash equivalents, restricted cash, and marketable securities	$ 1,134,256	$ 2,305,081
Deferred tax asset	571	1,169
Other assets	29,108	181,479
Assets	2,885,720	3,716,122
Operating Segments
Segment Reporting Information [Line Items]
Assets	$ 1,721,785	$ 1,228,393