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Retirement Benefit Plans - Amounts Included in Consolidated Balance Sheets from Obligation in Respect of Defined Benefit Plans (Detail)
$ in Millions, $ in Millions
Dec. 31, 2024
TWD ($)
Dec. 31, 2024
USD ($)
Dec. 31, 2023
TWD ($)
Dec. 31, 2022
TWD ($)
Dec. 31, 2021
TWD ($)
Disclosure of defined benefit plans [abstract]          
Present value of funded defined benefit obligations $ 27,985   $ 30,313    
Fair value of plan assets (34,762)   (34,178)    
Funded status - surplus (6,777)   (3,865)    
Net defined benefit liabilities 2,107 $ 64 2,098    
Net defined benefit assets (8,884) $ (271) (5,963)    
Defined benefit obligation $ (6,777)   $ (3,865) $ (2,981) $ (1,103)