Derivatives and Hedging Activities - Effect of Derivative Instruments on Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	$ 3.4	$ (4.3)	$ (11.5)
Designated as Hedging Instruments | Cash Flow Hedge
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	(0.7)	1.7	0.3
Designated as Hedging Instruments | Foreign Currency Forward Contracts | Cash Flow Hedge
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	(0.8)	1.6	0.2
Designated as Hedging Instruments | Treasury Lock | Cash Flow Hedge
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	0.1	0.1	0.1
Designated as Hedging Instruments | Interest Rate Swaps | Fair Value Hedging
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	0.0	0.6	0.5
Not Designated as Hedging Instruments | Foreign Currency Forward Contracts
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	$ 4.1	$ (6.6)	$ (12.3)