INCOME TAXES - Schedule of Reconciliation of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. Statutory federal income tax expense (benefit)	$ 34.4	$ (60.9)	$ (19.0)
Permanent items	8.1	5.0	(1.7)
Goodwill impairment	0.0	2.8	0.0
Foreign statutory rate vs. U.S. statutory rate	(3.7)	(1.6)	(4.7)
State income taxes, net of federal effect	(3.2)	(14.5)	(8.3)
State effective rate change	1.0	(4.0)	1.2
GILTI	5.0	2.1	16.5
GILTI impact of retroactive law changes and other	0.0	0.0	(3.2)
Residual tax on foreign earnings	1.9	1.5	4.8
Change in valuation allowance	1.9	0.2	3.6
Unrecognized tax expense	7.3	3.8	2.2
Share based compensation adjustments	0.3	0.3	(5.6)
Research and development tax credits	(2.3)	(1.8)	(1.9)
Partnership outside basis adjustment	7.7	7.0	1.2
Return to provision adjustments and other, net	5.9	3.6	1.6
Income tax expense (benefit)	$ 64.3	$ (56.5)	$ (13.3)