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Fair Value Information - Schedule of Carrying Amounts of Financial Assets and Liabilities Not Measured at Fair Value (Detail) - TWD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Corporate Bonds [Member]    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets, Carrying Value $ 2,000 $ 0
Financial assets, Fair Value 2,002 0
Bonds Payable [Member]    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities, Carrying Value 30,488 30,483
Financial liabilities, Fair Value $ 30,485 $ 30,469