Derivatives and Financial Instruments - Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contract liabilities	$ (30.8)	$ (30.6)
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contract liabilities	(30.8)	(30.6)
Deferred compensation plan	20.4	20.9
Total recurring fair value measurements	(10.4)	(9.7)
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contract liabilities	0.0	0.0
Deferred compensation plan	12.2	17.6
Total recurring fair value measurements	12.2	17.6
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contract liabilities	(30.8)	(30.6)
Deferred compensation plan	0.0	0.0
Total recurring fair value measurements	(30.8)	(30.6)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contract liabilities	0.0	0.0
Deferred compensation plan	0.0	0.0
Total recurring fair value measurements	0.0	0.0
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contract liabilities		0.0
Deferred compensation plan		3.3
Total recurring fair value measurements	$ 8.2	$ 3.3