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Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2020	Sep. 30, 2020	Dec. 31, 2015	Dec. 31, 2019
Income Tax Contingency [Line Items]
Unrecognized tax benefits would impact effective tax rate if recognized		$ 15.5
Unrecognized tax benefit		15.5		$ 16.4
Income tax interest expense		$ 0.1
Income tax examination, description		The Company and its U.S. subsidiaries remain open to examination by the IRS for years 2016 onwards under the statute of limitations. The Company’s subsidiaries in foreign tax jurisdictions are open to examination including Germany (2015 onwards), Switzerland (2015 onwards), Spain (2016 onwards), France (2017 onwards) and the United Kingdom (2018 onwards).
Increase to income tax expense		$ 0.5
Foreign exchange movements		0.1
Interest and Penalties [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefit		2.2		$ 2.0
Italian Tax Authorities [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefit		3.3
United States [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefit		$ 12.2
Non-US [Member] | Earliest Tax Year [Member]
Income Tax Contingency [Line Items]
Open tax year		2011
Non-US [Member] | Latest Tax Year [Member]
Income Tax Contingency [Line Items]
Open tax year		2014
Non-US [Member] | Historical Impairment Of Subsidiaries [Member]
Income Tax Contingency [Line Items]
Increase in uncertain tax positions			$ 1.2
Decrease in uncertain tax positions	$ 1.2
Non-US [Member] | Historical Impairment Of Subsidiaries [Member] | Interest and Penalties [Member]
Income Tax Contingency [Line Items]
Increase to income tax expense	$ (0.2)

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