COMPREHENSIVE INCOME (LOSS) - SUMMARY OF COMPREHENSIVE INCOME, NET OF TAX (Details) - Foreign Currency Translation Gain (Loss) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Statement of Income Captions [Line Items]
Foreign currency translation gains (losses)	$ 54.9	$ (223.4)	$ (17.0)	$ (139.4)
Net Investment Hedging
Condensed Statement of Income Captions [Line Items]
Foreign currency translation gains (losses)	$ (11.2)	$ 31.0	$ (0.6)	$ 12.1

Amount after tax, before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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