COMPREHENSIVE INCOME (LOSS) - SUMMARY OF COMPREHENSIVE INCOME, NET OF TAX (Details) - Foreign Currency Translation Gain (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Condensed Statement of Income Captions [Line Items]
Foreign currency translation gains (losses)	$ 107.1	$ (147.2)	$ 67.6	$ (164.2)
Foreign currency translation (losses) gains on hedges of net investments
Condensed Statement of Income Captions [Line Items]
Foreign currency translation gains (losses)	$ (22.3)	$ 19.7	$ (28.0)	$ 19.1