SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jul. 01, 2018	Jun. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 29.9			$ 30.6
Effective income tax rate (percent)	88.50%	61.10%
Driver of increase in effective tax rate	$ 30.0
Gross unrecognized tax benefits	304.7			303.6
Unrecognized tax benefits that would impact effective tax rate	125.8
Unrecognized tax benefits, net	140.2			135.4
Interest and penalties expense	1.2	$ 1.1
Gross accrued interest and penalties	14.3			$ 13.1
Reasonably possible decrease in UTBs (up to)	9.3
Income tax adjustment	77.4	25.3
Increase (decrease) in other current assets	(40.2)	$ 21.0
Accumulated deficit	769.1		$ 644.4
Accounting Standards Update 2016-06
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gross unrecognized tax benefits			15.8
Income tax adjustment	(7.6)
Increase (decrease) in other current assets	$ (120.8)
Accumulated deficit			$ 112.6