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Pension and Post-Employment Benefits - Unfunded Defined Benefit Pension Plan (Detail) - German Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Plan net pension charge:
Interest cost on PBO	$ 0.2	$ 0.2	$ 0.2
Amortization of actuarial net loss	0.4	0.4	0.2
Plan net pension (credit)/charge	$ 0.6	$ 0.6	$ 0.4
Plan assumptions at December 31, (%):
Discount rate	1.90%	1.70%	1.80%
Inflation rate	1.75%	1.75%	1.75%
Rate of increase in compensation levels	2.75%	2.75%	2.75%

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Defined benefit plan assumptions used calculating net periodic benefit cost inflation rate.

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- Definition

Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan.

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Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

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Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of net periodic benefit cost (credit) for defined benefit plan.

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