Income Taxes - Components of (Loss) Income Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Domestic	$ (24,524)	$ (168,452)	$ 20,933
Foreign	(11,865)	(30,299)	27,336
(Loss) income before income taxes	$ (36,389)	$ (198,751)	$ 48,269