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Investment Properties - Additional Information (Detail) - TWD ($)
$ in Millions
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Disclosure of detailed information about investment property [abstract]      
Reversal of impairment loss $ 139   $ 107
Impairment loss $ 139 $ 336 $ 9