XML 153 R130.htm IDEA: XBRL DOCUMENT v3.21.1
Capital stock - Additional Information (Detail)
$ / shares in Units, $ in Thousands, $ in Thousands
 12 Months Ended
Mar. 07, 2019
TWD ($)
Aug. 15, 2018
TWD ($)
shares
Dec. 31, 2020
TWD ($)
$ / shares
shares
Dec. 31, 2018
shares
Dec. 31, 2020
USD ($)
shares
Dec. 31, 2019
TWD ($)
Aug. 06, 2019
shares
Disclosure of classes of share capital [line items]              
Ordinary shares par value | $ / shares     $ 10        
Number of shares outstanding     727,240,000   727,240,000    
Percentage of capital reduction   15.00%          
Amount of capital reduction | $   $ 1,329,446          
Authorised capital | $     $ 9,700,000        
Number of shares authorised     970,000,000   970,000,000    
Paid in capital     $ 7,272,401   $ 258,989 $ 7,272,401  
Approval for number of treasury stock cancelled             25,570,000
Cancellation of treasury stock | $ $ 962,503            
Top of range [member]              
Disclosure of classes of share capital [line items]              
Share buyback as a percentage of the companies issued shares     10.00%   10.00% 10.00%  
Ordinary shares [member]              
Disclosure of classes of share capital [line items]              
Number of shares outstanding     85,412,000   85,412,000    
Capital reduction   132,945,000   (128,422,000)      
American depositary shares [member]              
Disclosure of classes of share capital [line items]              
Number of shares represented by each unit of ADS     20        
Number of shares outstanding     4,270,600   4,270,600