Income Taxes - Schedule of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Current:
Federal	$ 88,900	$ 15,100	$ 67,700
State	26,400	(78,600)	71,900
Foreign	56,100	63,500	52,800
Total current income tax expense	171,400	0	192,400
Deferred:
Federal	7,700	45,200	(71,800)
State	(6,500)	68,100	(84,300)
Foreign	31,400	39,600	19,800
Total deferred income tax expense (benefit)	32,600	152,900	(136,300)
Total income tax expense	$ 204,018	$ 152,900	$ 56,052