Revenue from Contracts with Customers - Revenue By Geographic Segment (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Total revenue	$ 2,097,053	$ 1,933,347	$ 1,807,159
United States
Total revenue	993,800	864,700	741,300
Germany
Total revenue	$ 292,000	$ 318,500	$ 290,700