FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Noncontrolling interest puts	$ 15.4	$ 15.0
Fair market value of zero-coupon subordinated notes	1.8	16.9
Fair market value of senior notes	5,508.6	5,318.0
Cash Surrender Value, Fair Value Disclosure	71.0	63.5
Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability	71.6	64.2
Contingent Consideration Classified as Equity, Fair Value Disclosure	18.6	18.6
Fair Value Hedges, Net	0.6
Foreign Currency Contract, Asset, Fair Value Disclosure	9.0	2.8
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	0.0	2.1
Level 1 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Noncontrolling interest puts	0.0	0.0
Cash Surrender Value, Fair Value Disclosure	0.0	0.0
Contingent Consideration Classified as Equity, Fair Value Disclosure	0.0	0.0
Fair Value Hedges, Net	0.0	0.0
Foreign Currency Contract, Asset, Fair Value Disclosure	0.0	0.0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Noncontrolling interest puts	15.4	15.0
Cash Surrender Value, Fair Value Disclosure	71.0	63.5
Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability	0.0	0.0
Contingent Consideration Classified as Equity, Fair Value Disclosure	0.0	0.0
Fair Value Hedges, Net	0.6	3.1
Foreign Currency Contract, Asset, Fair Value Disclosure	9.0	2.8
Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Noncontrolling interest puts	0.0	0.0
Cash Surrender Value, Fair Value Disclosure	0.0	0.0
Fair Value Liabilities Measured On Recurring Basis Deferred Compensation Liability	0.0	0.0
Contingent Consideration Classified as Equity, Fair Value Disclosure	18.6	18.6	$ 16.5
Fair Value Hedges, Net	0.0	0.0
Foreign Currency Contract, Asset, Fair Value Disclosure	$ 0.0	$ 0.0