DEBT - Tendered Notes and Redemption of 2026 Notes (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
(Gain) loss from early extinguishment of debt	$ (2.6)	$ 3.0	$ 0.0
Tendered Notes
Debt Instrument [Line Items]
Amounts Tendered	1,174.4
Amounts Paid	1,166.5
Premium (Discount) Realized	(7.9)
Unamortized Debt Issuance Costs	10.1
(Gain) loss from early extinguishment of debt	2.2
2026 Notes
Debt Instrument [Line Items]
Amounts Tendered	462.0
Amounts Paid	462.1
Premium (Discount) Realized	0.1
Unamortized Debt Issuance Costs	2.2
(Gain) loss from early extinguishment of debt	2.3
2029 Notes
Debt Instrument [Line Items]
Amounts Tendered	284.2
Amounts Paid	284.2
Premium (Discount) Realized	0.0
Unamortized Debt Issuance Costs	2.9
(Gain) loss from early extinguishment of debt	2.9
2030 Notes
Debt Instrument [Line Items]
Amounts Tendered	142.5
Amounts Paid	142.5
Premium (Discount) Realized	0.0
Unamortized Debt Issuance Costs	2.0
(Gain) loss from early extinguishment of debt	2.0
2031 Notes
Debt Instrument [Line Items]
Amounts Tendered	285.7
Amounts Paid	277.7
Premium (Discount) Realized	(8.0)
Unamortized Debt Issuance Costs	3.0
(Gain) loss from early extinguishment of debt	$ (5.0)