SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) € in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 25, 2019 EUR (€)	Jul. 01, 2019 USD ($)	Jun. 30, 2019 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 50.7		$ 50.7				$ 40.0
Effective income tax rate, percentage	55.70%	(8.90%)	(324.50%)	(0.10%)
Effective income tax rate reconciliation, resolution of foreign uncertain tax positions, amount	$ 11.8		$ 11.8
Gross unrecognized tax benefits	326.9		326.9				336.1
Unrecognized tax benefits that would impact effective tax rate	151.9		151.9
Unrecognized tax benefits, net	169.3		169.3				179.9
Interest and penalties expense	(1.3)	$ 1.5	0.1	$ 2.7
Gross accrued interest and penalties	17.4		17.4				$ 17.3
Reasonably possible decrease in UTBs (up to)	$ 17.8		$ 17.8
Recourse obligation, percentage of net invoice value (up to)	10.00%		10.00%
Receivables purchase agreement, facility limit | €					€ 93.0
Total present value of lease liabilities	$ 563.5		$ 563.5
Operating lease right-of-use assets	$ 505.7		$ 505.7
Adoption of ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment due to the adoption of new accounting principle						$ (0.7)
Total present value of lease liabilities						617.8
Operating lease right-of-use assets						551.3
Retained Earnings | Adoption of ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment due to the adoption of new accounting principle						(0.7)
Unamortized Lease Incentives and Lease Loss Liabilities | Adoption of ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment due to the adoption of new accounting principle						$ (66.4)