RESTRUCTURING COSTS - Summary of Global Initiative Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred	$ 21.7	$ 15.8	$ 32.9	$ 23.2
Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred	27.1	$ 13.6	36.9	$ 13.6	$ 364.2
Restructuring costs incurred to date	401.1		401.1
Severance and Employee Benefits | Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred			24.2		333.9
Restructuring costs incurred to date	358.1		358.1
Third-Party Contract Terminations | Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred			9.4		22.4
Restructuring costs incurred to date	31.8		31.8
Fixed Asset Write-offs | Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred			0.2		4.6
Restructuring costs incurred to date	4.8		4.8
Other Exit Costs | Global Integration Activities
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred			3.1		$ 3.3
Restructuring costs incurred to date	$ 6.4		$ 6.4