Goodwill and Intangible Assets - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Balance	$ 890,802	$ 1,128,511
Goodwill impairment		(213,720)
Effect of foreign currency translation	9,540	(23,989)
Balance	$ 900,342	$ 890,802