Changes in Accumulated Other Comprehensive Income/(Loss) by Component - Reconciliation of Changes in Accumulated Other Comprehensive Income/(Loss) by Component (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss) by Component	$ (89.9)
Beginning balance	1,922.3	$ 1,848.2
Net current-period Other Comprehensive Income (Loss)	(38.9)	(1.3)
Accumulated Other Comprehensive Income (Loss) by Component	(128.8)
Ending balance	1,757.1	1,872.4
Gains and Losses on Cash Flow Hedges [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss) by Component	(3.0)	(12.9)
Net current-period Other Comprehensive Income (Loss)	19.6	11.5
Accumulated Other Comprehensive Income (Loss) by Component	16.6	(1.4)
Defined Benefit Pension Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss) by Component	(1.5)	(0.2)
Net current-period Other Comprehensive Income (Loss)	(0.1)	(0.3)
Accumulated Other Comprehensive Income (Loss) by Component	(1.6)	(0.5)
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss) by Component	(85.4)	(58.5)
Net current-period Other Comprehensive Income (Loss)	(58.4)	(12.5)
Accumulated Other Comprehensive Income (Loss) by Component	(143.8)	(71.0)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(89.9)	(71.6)
Ending balance	$ (128.8)	$ (72.9)