INCOME TAXES - Schedule of Components of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Current tax expense:
U.S. Federal	$ 27.4	$ 81.8	$ 7.7
Foreign	31.9	44.9	24.7
State and local	1.3	(0.4)	(1.1)
Total current tax expense	60.6	126.3	31.3
Deferred tax expense (benefit):
U.S. Federal	6.2	(197.7)	(26.5)
Foreign	1.2	5.0	(1.2)
State and local	(3.7)	9.9	(16.9)
Total deferred tax expense (benefit)	3.7	(182.8)	(44.6)
Income tax expense (benefit)	$ 64.3	$ (56.5)	$ (13.3)