CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) income	$ (310,826)	$ 45,893	$ (18,316)
Other comprehensive (loss) income:
Foreign currency translation adjustments	(37,179)	(1,980)	15,805
Pension adjustments, net	2,233	(87)	1,178
Unrealized loss on available-for-sale securities	(425)	(10)	(1)
Total other comprehensive (loss) income	(35,371)	(2,077)	16,982
Comprehensive (loss) income	$ (346,197)	$ 43,816	$ (1,334)