Derivative Instruments and Hedging Activities - Net Investment Hedge Gains (Losses) Recognized on Condensed Consolidated Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain / (Loss) Recognized in AOCI	$ (158.2)	$ 124.2	$ (131.0)	$ 147.8
Euro Notes [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain / (Loss) Recognized in AOCI	(74.1)	48.6	(75.0)	53.0
Cross-currency Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain / (Loss) Recognized in AOCI	$ (84.1)	$ 75.6	$ (56.0)	$ 94.8