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Financial Risk Management Objectives - Additional Information (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Disclosure Of Financial Instruments [Line Items]        
Copper costs as a percentage of product cost 83.00% 82.00%    
Cash and cash equivalents $ 52,237 $ 53,673 $ 60,778 $ 46,093
Unutilized amounts of bank loans 200,000      
Financial liabilities 56,000      
Mortgage of land, buildings, machinery and equipment, investment properties and land use rights 15,078 15,099    
Pledge of other receivables 1,363 4,847    
Assets pledged as security   1,339    
Subsidiary [Member]        
Disclosure Of Financial Instruments [Line Items]        
Assets pledged as security $ 31,989 $ 27,454    
One major customer [Member]        
Disclosure Of Financial Instruments [Line Items]        
Percentage of trade receivables from one customer 14.76% 9.31%    
Interest rate risk [Member]        
Disclosure Of Financial Instruments [Line Items]        
Change of interest rates 0.30% 0.30%    
Change in profit before tax due to change of interest rates $ 54 $ 46    
Top Of Range [Member]        
Disclosure Of Financial Instruments [Line Items]        
Percentage of financial liabilities bear floating interest rate 14.00%      
Weighted average [Member]        
Disclosure Of Financial Instruments [Line Items]        
Weighted average interest rates on bank loans and overdrafts 2.07% 3.72%