CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (588,078)	$ (56,254)	$ (310,826)
Other comprehensive income (loss):
Foreign currency translation adjustments	2,343	5,620	(37,179)
Pension adjustments, net	(539)	(66)	2,233
Unrealized gain (loss) on available-for-sale securities	250	217	(425)
Total other comprehensive income (loss)	2,054	5,771	(35,371)
Comprehensive loss	$ (586,024)	$ (50,483)	$ (346,197)