Fair Value Measurements - Carrying Amount and Fair Values of the Company's Assets and Liabilities Measured on a Recurring Basis (Detail) - Recurring [Member] - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Carrying Amount [Member]
Non-derivatives:
Cash and cash equivalents	$ 167.1	$ 136.9
Short-term investments	0.0	4.8
Non-derivatives:
Long-term debt (including current portion)	143.0	133.0
Finance leases (including current portion)	4.5	3.1
Carrying Amount [Member] | Derivatives (Level 1 Measurement) [Member] | Foreign Currency Forward Exchange Contracts [Member]
Derivatives (Level 1 measurement):
Foreign currency forward exchange contracts	0.6	0.3
Carrying Amount [Member] | Non-financial Assets and Liabilities (Level 3 Measurement) [Member]
Non-financial liabilities (Level 3 measurement):
Acquisition-related contingent consideration	4.3	54.6
Stock equivalent units	9.1	7.8
Fair Value [Member]
Non-derivatives:
Cash and cash equivalents	167.1	136.9
Short-term investments	0.0	4.8
Non-derivatives:
Long-term debt (including current portion)	143.0	133.0
Finance leases (including current portion)	4.5	3.1
Fair Value [Member] | Derivatives (Level 1 Measurement) [Member] | Foreign Currency Forward Exchange Contracts [Member]
Derivatives (Level 1 measurement):
Foreign currency forward exchange contracts	0.6	0.3
Fair Value [Member] | Non-financial Assets and Liabilities (Level 3 Measurement) [Member]
Non-financial liabilities (Level 3 measurement):
Acquisition-related contingent consideration	4.3	54.6
Stock equivalent units	$ 9.1	$ 7.8