COMPREHENSIVE INCOME - ADDITIONAL INFORMATION (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Cumulative foreign currency translation adjustment gain (loss)	$ 6,705.2	$ 6,627.9	$ 8,163.6	$ 8,125.9
Foreign Currency Translation Gain (Loss)
Derivative [Line Items]
Foreign currency tax adjustment	195.2	203.8
Cumulative foreign currency translation adjustment gain (loss)	(39.4)	(104.5)	$ (440.7)	$ (490.5)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest, Translation Gain (Loss)
Derivative [Line Items]
Cumulative foreign currency translation adjustment gain (loss)	106.1	22.1
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest, Net Investment Hedges
Derivative [Line Items]
Cumulative foreign currency translation adjustment gain (loss)	$ (145.5)	$ (126.6)