Fair Value Measurement of Assets and Liabilities - Fair Value Measurements of Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	$ 8.9	$ 6.1
Contingent payments related to acquisitions	26.9	41.0
Total Liabilities	100.0	91.9
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	8.9	6.1
Total Liabilities	73.1	50.9
Fair Value Measurements at Reporting Date Using: Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payments related to acquisitions	26.9	41.0
Total Liabilities	26.9	41.0
Foreign Exchange Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, current and long-term	0.6	1.6
Derivatives, current and long-term	73.1	50.9
Foreign Exchange Forward Contracts [Member] | Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, current and long-term	0.6	1.6
Derivatives, current and long-term	73.1	50.9
Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, current and long-term	8.3	4.5
Interest Rate Swaps [Member] | Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, current and long-term	$ 8.3	$ 4.5