Segment Information - Schedule of Net Long-Lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment - net	$ 673	$ 535
Taiwan
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment - net	593	409
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment - net	32	49
Japan
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment - net	27	54
China
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment - net	13	19
South Korea
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment - net	$ 8	$ 4