Retirement Plans - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Health and welfare plans expense	$ 0.5	$ 0.5	$ 1.6	$ 1.3

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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