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Fair Value Information - Schedule of Carrying Amounts of Financial Assets and Liabilities Not Measured at Fair Value (Detail) - Bonds Payable [Member] - TWD ($)
$ in Millions
Dec. 31, 2021
Dec. 31, 2020
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Carrying Value $ 26,977 $ 19,980
Fair Value $ 27,082 $ 20,078