Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 245,540	$ 313,081	$ 476,923
Other comprehensive income (loss), net of tax:
Hedge gain (loss) arising during the period, net of tax of $2.5 million, $(5.8) million, and $(0.4) million in 2023, 2022, and 2021, respectively	(7,516)	17,556	1,248
Foreign currency translation adjustment, net of tax of $0 for each period	45,692	(92,768)	1,613
Unrealized loss on marketable securities, net of tax of $0 for each period	0	0	(307)
Amortization of net actuarial pension loss included in net income, net of tax of $(0.1) million, $(0.4) million, and $(1.2) million in 2023, 2022, and 2021, respectively	161	1,010	2,930
Pension net gain (loss) and plan amendments arising during the period, net of tax of $1.3 million, $(6.1) million, and $(0.7) million in 2023, 2022, and 2021, respectively	(2,642)	15,027	1,891
Change in unamortized pension loss during the period related to changes in foreign currency, net of tax of $0.1 million, $(0.6) million, and $0.0 million in 2023, 2022, and 2021, respectively	(317)	1,581	135
Other comprehensive income (loss)	35,378	(57,594)	7,510
Comprehensive income	$ 280,918	$ 255,487	$ 484,433