RESTRUCTURING COSTS - Restructuring Costs by Type (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 6.0	$ 15.5
2018 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring costs	(0.8)		$ 16.8	$ 68.4
Restructuring and Related Cost, Cost Incurred to Date	84.4
Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring costs	(1.7)	6.5	28.5	106.5	$ 365.0
Restructuring and Related Cost, Cost Incurred to Date	498.3
Turnaround Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs	8.7	$ 0.0
Restructuring and Related Cost, Cost Incurred to Date	8.7
Severance and Employee Benefits | 2018 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring costs	(0.8)		15.4	63.5
Restructuring and Related Cost, Cost Incurred to Date	78.1
Severance and Employee Benefits | Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring costs	(1.7)		(6.0)	67.5	333.9
Restructuring and Related Cost, Cost Incurred to Date	393.7
Severance and Employee Benefits | Turnaround Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	7.1
Third-Party Contract Terminations | 2018 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.0		(0.1)	0.2
Restructuring and Related Cost, Cost Incurred to Date	0.1
Third-Party Contract Terminations | Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.0		4.5	19.3	22.4
Restructuring and Related Cost, Cost Incurred to Date	46.2
Third-Party Contract Terminations | Turnaround Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.1
Fixed Asset Write-offs | 2018 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.0		0.0	1.3
Restructuring and Related Cost, Cost Incurred to Date	1.3
Fixed Asset Write-offs | Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.0		27.8	14.3	4.6
Restructuring and Related Cost, Cost Incurred to Date	46.7
Fixed Asset Write-offs | Turnaround Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.1
Other Exit Costs | 2018 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.0		1.5	3.4
Restructuring and Related Cost, Cost Incurred to Date	4.9
Other Exit Costs | Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0.0		$ 2.2	$ 5.4	$ 4.1
Restructuring and Related Cost, Cost Incurred to Date	11.7
Other Exit Costs | Turnaround Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	$ 1.4