RETIREMENT PLANS - Fair Value of The Company's Pension Plan Asset (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
U.S. Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 80.7	$ 87.5	$ 89.4
U.S. Plan | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.6	2.4
U.S. Plan | Mutual funds | Mutual funds—real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.2	3.7
U.S. Plan | Mutual funds | Mutual funds—equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18.0	22.5
U.S. Plan | Mutual funds | Mutual funds—fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	56.9	58.9
U.S. Plan | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.6	2.4
U.S. Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.6	2.4
U.S. Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds | Mutual funds—real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds | Mutual funds—equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds | Mutual funds—fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Plan | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	78.1	85.1
U.S. Plan | Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Plan | Significant Other Observable Inputs (Level 2) | Mutual funds | Mutual funds—real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.2	3.7
U.S. Plan | Significant Other Observable Inputs (Level 2) | Mutual funds | Mutual funds—equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18.0	22.5
U.S. Plan | Significant Other Observable Inputs (Level 2) | Mutual funds | Mutual funds—fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	56.9	58.9
U.S. Plan | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Plan | Unobservable Inputs (Level 3) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Plan | Unobservable Inputs (Level 3) | Mutual funds | Mutual funds—real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Plan | Unobservable Inputs (Level 3) | Mutual funds | Mutual funds—equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Plan | Unobservable Inputs (Level 3) | Mutual funds | Mutual funds—fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	181.5	181.2	$ 173.9
International Plan | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.0	0.4
International Plan | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.5	4.7
International Plan | Mutual funds | Mutual funds—equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61.2	56.7
International Plan | Mutual funds | Mutual funds—fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	114.8	119.4
International Plan | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.0	0.4
International Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.0	0.4
International Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds | Mutual funds—equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds | Mutual funds—fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	180.5	180.8
International Plan | Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan | Significant Other Observable Inputs (Level 2) | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.5	4.7
International Plan | Significant Other Observable Inputs (Level 2) | Mutual funds | Mutual funds—equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61.2	56.7
International Plan | Significant Other Observable Inputs (Level 2) | Mutual funds | Mutual funds—fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	114.8	119.4
International Plan | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan | Unobservable Inputs (Level 3) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan | Unobservable Inputs (Level 3) | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan | Unobservable Inputs (Level 3) | Mutual funds | Mutual funds—equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Plan | Unobservable Inputs (Level 3) | Mutual funds | Mutual funds—fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0.0	$ 0.0