XML 201 R185.htm IDEA: XBRL DOCUMENT v3.21.1
Net Income - Interest Expenses (Detail)
$ in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2020
TWD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
TWD ($)
Dec. 31, 2018
TWD ($)
Interest Costs [Abstract]        
Interest paid to financial institutions $ 79   $ 17 $ 16
Interest on lease liabilities 80   85 0
Interest on bonds payable 46   0 0
Others 1   2 2
Interest expenses $ 206 $ 7 $ 104 $ 18