VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Inventory obsolescence expense	$ 22.2	$ 116.0	$ 180.5
Allowance for doubtful accounts receivable
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	66.6	93.0	129.3
Charged to Costs and Expenses	78.3	115.4	162.4
Charged to Revenue	0.0	0.0	0.0
Deductions	(93.8)	(141.8)	(198.7)
Balance at End of Period		66.6	93.0
Refund liability
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	10.7
Charged to Costs and Expenses	0.0
Charged to Revenue	101.4
Deductions	(103.0)
Balance at End of Period	9.1	10.7
Refund liability
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	10.7	12.3	9.3
Charged to Costs and Expenses		0.0	0.0
Charged to Revenue		132.6	172.3
Deductions		(134.2)	(169.3)
Balance at End of Period		10.7	12.3
Allowance for inventory obsolescence
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	82.0	146.1	61.3
Charged to Costs and Expenses	37.9	37.1	113.5
Charged to Revenue	0.0	0.0	0.0
Deductions	(49.5)	(101.2)	(28.7)
Balance at End of Period	70.4	82.0	146.1
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	2,960.0	3,257.5	3,217.6
Charged to Costs and Expenses	(632.4)	(297.5)	39.9
Charged to Revenue	0.0	0.0	0.0
Deductions	0.0	0.0	0.0
Balance at End of Period	$ 2,327.6	$ 2,960.0	3,257.5
Inventory write-off
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Inventory obsolescence expense			$ 88.0