Revenue from Contracts with Customers - Revenue By Geographic Segment (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Revenue Reconciling Item [Line Items]
Total revenue		$ 2,739,226	$ 2,298,472	$ 2,097,053
Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Total revenue		2,739,226	2,298,472	2,097,053
Americas | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Total revenue	[1]	1,327,229	1,087,929	1,023,273
Europe | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Total revenue	[2]	995,094	859,387	753,796
Asia Pacific | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Total revenue		$ 416,903	$ 351,156	$ 319,984

[1] Includes revenue in the United States totaling $1,287.5 million, $1,057.3 million, and $993.8 million for 2025, 2024 and 2023, respectively.

[2] Includes revenue in Germany totaling $368.8 million, $330.5 million, and $292.0 million for 2025, 2024 and 2023, respectively.