Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	$ 0	$ 0	$ 140
Deferred Tax Assets, Valuation Allowance	13,044	$ 12,234	$ 13,179	$ 7,832
China
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	10,186
United States
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	10,408
ITALY
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	5,468
Deferred Tax Assets, Valuation Allowance	$ 1,312