Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 58,832	$ 74,302
United States
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	8,608	16,751
People's Republic of China (PRC)
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	14,799	13,700
Asia (excluding the PRC)
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	9,808	21,691
Europe
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	15,185	9,081
South America
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 10,432	$ 13,079