Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Contract with Customer, Liability [Roll Forward]
Beginning contract liability	$ 51,649	$ 65,460	$ 46,610
Revenue recognized from contract liabilities included in the beginning balance	(48,642)	(63,207)	(43,777)
Increases due to business combinations and cash received, net of amounts recognized in revenue during the period	60,948	49,396	62,627
Ending contract liability	63,955	51,649	$ 65,460
Allowance for credit loss, current	$ 4,200	$ 4,400