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Net Operating Loss Carryforwards available to Offset Future Taxable Income (Detail)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
USD ($)
Operating Loss Carryforwards [Line Items]  
Amount $ 54,948
Hong Kong  
Operating Loss Carryforwards [Line Items]  
Amount $ 15,759
Expiring year Indefinite
Taiwan  
Operating Loss Carryforwards [Line Items]  
Amount $ 39,189
Taiwan | Earliest Tax Year  
Operating Loss Carryforwards [Line Items]  
Expiring year 2020
Taiwan | Latest Tax Year  
Operating Loss Carryforwards [Line Items]  
Expiring year 2029