XML 137 R100.htm IDEA: XBRL DOCUMENT v3.20.1
Property, Plant and Equipment - Additional Information (Detail) - TWD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Bottom of range [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Operating lease term 1 year  
Top of range [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Operating lease term 5 years  
Main plants [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated useful lives for property, plant and equipment 20 years 20 years
Mechanical and electrical power equipment [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated useful lives for property, plant and equipment 10 years 10 years
Clean rooms [member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Estimated useful lives for property, plant and equipment 10 years 10 years
Machinery and equipment    
Disclosure of detailed information about property, plant and equipment [line items]    
Impairment loss recognized $ 301.4 $ 423.5