Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Valuation allowance, deferred tax asset, change in amount		$ 20,400,000
Unrecognized tax benefits		1,202,000	$ 1,048,000	$ 862,000	$ 606,000
Accrued interest or penalties related to uncertain tax positions		$ 0	$ 0
Statutory income tax rate		34.00%	34.00%	34.00%
Decrease in deferred tax assets due to newly enacted tax rate		$ 36,100,000
Decrease in valuation allowance due to newly enacted tax rate		36,100,000
Scenario, Plan [Member]
Income Tax Contingency [Line Items]
Statutory income tax rate	21.00%
Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards		254,600,000
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards		$ 204,800,000
Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards expiration period		2023
Foreign Tax Authority [Member] | Italy
Income Tax Contingency [Line Items]
Operating loss carry forwards		$ 15,600,000
Foreign Tax Authority [Member] | Luxembourg [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards		200,000
Foreign Tax Authority [Member] | Switzerland [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards		$ 16,700,000
Maximum [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards expiration period		2027
Minimum [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards expiration period		2022
Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax credit carry forward, amount		$ 5,500,000
Tax credit carry forward expiration period		2027