SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Significant Accounting Policies [Line Items]
Restricted cash	$ 56.9	$ 43.7
Sales returns, percentage	2.00%	3.00%	2.00%
Trade spending activities, percentage	10.00%	11.00%	9.00%
Advertising expense	$ 1,029.4	$ 1,343.7	$ 1,595.5
Depreciation and amortization	334.1	351.7	331.8
Research and development expense	96.5	93.4	98.5
Net (losses) gains from foreign currency exchange transactions	(26.7)	(30.5)	4.2
Cumulative-effect adjustment	(3,062.2)	(3,228.8)	(4,593.4)	$ (8,855.2)
Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment		5.7	0.7	18.2
Accumulated Deficit
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment	5,755.6	5,548.6	4,541.2	626.2
Accumulated Deficit | Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment		5.7	0.7	$ 18.2
Accumulated Deficit | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment		5.7
Accumulated Deficit | Cumulative Effect, Period Of Adoption, Pre-Tax Adjustment | Accounting Standards Update 2016-13
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment		6.6
Operating Income (Loss)
Significant Accounting Policies [Line Items]
Net (losses) gains from foreign currency exchange transactions	(7.8)	(18.0)	(2.7)
Interest Expense, Net and Other Expense (Income), Net
Significant Accounting Policies [Line Items]
Net (losses) gains from foreign currency exchange transactions	$ (6.8)	(14.8)	7.6
Store fixtures | Minimum
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated useful life	3 years
Store fixtures | Maximum
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated useful life	5 years
Marketing furniture and fixtures
Significant Accounting Policies [Line Items]
Depreciation and amortization	$ 130.3	$ 127.9	$ 120.4
Marketing furniture and fixtures | Minimum
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated useful life	3 years
Marketing furniture and fixtures | Maximum
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated useful life	5 years