Summary of Fair Value of Company's Plan Assets (Detail) - Fair Value, Inputs, Level 2 - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 78.5	$ 88.1
Total	350.8	382.7
Non-U.S. Bonds | Corporate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61.4	66.9
Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12.6	13.8
Common Collective Trusts
Defined Benefit Plan Disclosure [Line Items]
Investments measured at net asset value	272.3	294.6
Other Investment
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 4.5	$ 7.4