INCOME TAXES - Reconciliation of the Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 25.7	$ 34.6	$ 35.8
Additions for tax positions of the current year	0.2	0.2	0.2
Additions for tax positions of prior years	0.0	0.1	3.8
Reductions for tax positions of prior years	0.0	(3.7)	(0.2)
Settlements with tax authorities	0.0	(0.7)	(0.1)
Expiration of statutes of limitation	(3.1)	(4.8)	(4.9)
Balance at end of year	$ 22.8	$ 25.7	$ 34.6