COMPREHENSIVE INCOME (LOSS) - ADDITIONAL INFORMATION (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Cumulative foreign currency translation adjustment gain (loss)	$ 4,762.3	$ 4,645.4	$ 4,690.2	$ 5,094.9	$ 5,059.1	$ 5,182.9	$ 5,109.5	$ 5,133.0
Foreign Currency Translation Gain (Loss)
Derivative [Line Items]
Foreign currency tax adjustment	189.5			173.0
Cumulative foreign currency translation adjustment gain (loss)	(328.7)			(368.3)	$ (429.8)			$ (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)	(192.6)			(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)	$ (136.1)			$ (108.1)