EMPLOYEE BENEFIT PLANS - Fair Value of Pension Plan Assets by Asset Category (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 151.7	$ 143.4
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33.6	34.6
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	107.7	98.2
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.4	10.6
Cash & cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.3	0.2
Cash & cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.3	0.2
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	10.3	11.0
Equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.6	4.9
Equity | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.7	6.1
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	32.0	33.2
Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24.2	25.1
Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.8	8.1
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	4.5	4.4
Foreign equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.5	4.4
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	50.8	39.4
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	50.8	39.4
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	40.7	36.7
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	40.7	36.7
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	10.4	10.6
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	10.4	10.6
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.7	7.9
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	2.7	7.9
Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0.0	$ 0.0