COMPREHENSIVE INCOME (LOSS) - ADDITIONAL INFORMATION (Details) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Cumulative foreign currency translation adjustment gain (loss)	$ 4,645.4	$ 4,690.2	$ 5,094.9	$ 5,182.9	$ 5,109.5	$ 5,133.0
Foreign Currency Translation Gain (Loss)
Derivative [Line Items]
Foreign currency tax adjustment	172.0		173.0
Cumulative foreign currency translation adjustment gain (loss)	(413.5)		(368.3)	$ (302.3)		$ (284.7)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest, Translation Gain (Loss)
Derivative [Line Items]
Cumulative foreign currency translation adjustment gain (loss)	(299.7)		(260.2)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest, Net Investment Hedges
Derivative [Line Items]
Cumulative foreign currency translation adjustment gain (loss)	$ (113.8)		$ (108.1)