XML 165 R164.htm IDEA: XBRL DOCUMENT v3.20.1
Pledged Assets - Additional Information (Detail) - TWD ($)
$ in Millions
Dec. 31, 2019
Dec. 31, 2018
Certificates of deposit [member]    
Disclosure of Pledged Assets [Line Items]    
Financial assets pledged as collateral $ 114.5 $ 124.2