EMPLOYEE BENEFIT PLANS - Schedule of Fair Value of Pension Plan Assets by Asset Category (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 162.6	$ 151.7
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41.1	33.6
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	121.5	107.7
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	10.4
Cash & cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.3	0.3
Cash & cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.3	0.3
Cash & cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Cash & cash equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.9	10.3
Equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.5	4.6
Equity | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.4	5.7
Equity | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40.4	32.0
Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33.3	24.2
Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.1	7.8
Fixed Income Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Foreign equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.0	4.5
Foreign equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.0	4.5
Foreign equity | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Foreign equity | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Foreign fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	60.5	50.8
Foreign fixed income securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Foreign fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	60.5	50.8
Foreign fixed income securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Life insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47.0	40.7
Life insurance contracts | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Life insurance contracts | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47.0	40.7
Life insurance contracts | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Annuity policy
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	10.4
Annuity policy | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Annuity policy | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Annuity policy | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	10.4
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.5	2.7
Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.5	2.7
Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0.0	$ 0.0