XML 230 R211.htm IDEA: XBRL DOCUMENT v3.21.1
Related Party Transactions - Additional Information (Detail)
$ in Thousands, $ in Thousands
 1 Months Ended 12 Months Ended
Sep. 30, 2020
TWD ($)
shares
Jul. 31, 2019
TWD ($)
shares
Jul. 31, 2019
USD ($)
shares
Dec. 31, 2020
TWD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
TWD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2018
TWD ($)
Dec. 31, 2018
USD ($)
ASE Cultural and Educational Foundation [member] | Environmental charity [member]                  
Disclosure of transactions between related parties [line items]                  
Amount contributed related party transactions       $ 100,000 $ 3,561 $ 100,000 $ 3,561 $ 100,000 $ 3,561
Associates [member]                  
Disclosure of transactions between related parties [line items]                  
Real estate properties acquired | $           $ 2,326,000      
ASE Environmental Protection And Sustainability Foundation [Member] | Environmental Protection Project [Member]                  
Disclosure of transactions between related parties [line items]                  
Amount contributed related party transactions       $ 100,000 $ 3,561        
USI Enterprise Limited [member]                  
Disclosure of transactions between related parties [line items]                  
Repurchase of outstanding ordinary shares | shares | shares 2,685 2,805 2,805            
Value of ordinary shares purchased $ 1,520,976 $ 1,247,187 $ 54,166