SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Dec. 22, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Jul. 01, 2018	Jun. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash		$ 27.5		$ 27.5			$ 30.6
Effective income tax rate (percent)		(8.90%)	(7.10%)	(0.10%)	(47.90%)
Tax Cuts And Jobs Act Of 2017, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense (benefit)	$ 41.0
Gross unrecognized tax benefits		$ 317.6		$ 317.6			303.6
Unrecognized tax benefits that would impact effective tax rate		126.8		126.8
Unrecognized tax benefits, net		142.5		142.5			135.4
Interest and penalties expense		1.5	$ 1.0
Gross accrued interest and penalties		15.7		15.7			13.1
Reasonably possible decrease in UTBs (up to)		25.4		25.4
Provision (benefit) for income taxes		78.3	$ (7.9)	0.9	$ (33.2)
Increase (decrease) in other current assets				(19.7)	$ 47.6
Accumulated deficit		1,729.7		$ 1,729.7		$ 644.4	$ 626.2
Accounting Standards Update 2016-06
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gross unrecognized tax benefits						15.8
Provision (benefit) for income taxes		7.6
Increase (decrease) in other current assets		$ (120.8)
Accumulated deficit						$ 112.6