DEBT - COVERTIBLE SUBORDINATED NOTES (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Nov. 25, 2019	Sep. 15, 2017
Debt Instrument [Line Items]
2017 Term loan		$ 0.0	$ 527.1			$ 750.0
Notes Payable, Noncurrent		7.0	7.1
Convertible Subordinated Debt, Current		0.0	8.7
Short term debt issuance costs		(0.7)	(0.5)
Notes Payable, Current		2.2	1.8
Long-term debt, less current portion		5,789.8	5,990.9
Senior notes due 2024		600.0	600.0
Senior Notes, Noncurrent					$ 1,050.0
Foreign Currency Contract, Asset, Fair Value Disclosure		(3.2)	(2.8)
Debt, Current		$ 415.2	$ 10.0
Common stock issued upon conversion of zero-coupon subordinated notes (in shares)		0.1	0.0	0.3
Cross currency swap maturing 2025 [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount		$ 300.0
Senior notes due 2024 [Member] [Member]
Debt Instrument [Line Items]
Long-term debt, less current portion		400.0
Senior notes due 2027 [Member]
Debt Instrument [Line Items]
Long-term debt, less current portion		600.0	$ 600.0
Cross currency swap maturing 2022 [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount		300.0
Zero-coupon convertible subordinated notes [Member]
Debt Instrument [Line Items]
Principal amount at maturity of zero-coupon subordinated notes outstanding			8.6
Principal Amount At Maturity Of Zero Coupon Subordinated Notes Converted		8.6	0.3
Value Of Cash And Common Stock In Connection With Conversions Of Zero Coupon Subordinated Notes Settled In Current Period		16.6	0.7
Payments On Zero Coupon Subordinated Notes		$ 8.2	$ 0.3
Common stock issued upon conversion of zero-coupon subordinated notes (in shares)		0.1	0.0
Tax Benefit Realized Upon Conversion Of Zero Coupon Convertible Debt		$ 2.0	$ 0.2
Contingent cash interest accrual rate	0.125%
Number of days used to establish average market price of zero coupon subordinated notes	5