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Retirement Benefit Plans - Additional Information (Detail) - TWD ($)
$ in Millions
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Disclosure of defined benefit plans [line items]      
Employer contribution percentage, defined contribution plans 6.00%    
Defined contribution plans expense $ 5,932.2 $ 5,365.5 $ 4,550.4
Employer contribution percentage, defined benefit plans 2.00%    
Defined benefit plans contribution in the next year $ 870.0    
Weighted average duration of the defined benefit obligation 8 years    
Actuarial assumption of discount rates [member]      
Disclosure of defined benefit plans [line items]      
Amount of increase in defined benefit obligation $ 717.5 757.7  
Actuarial assumption of expected rates of salary increases [member]      
Disclosure of defined benefit plans [line items]      
Percentage of increase in salary rate 0.50%    
Amount of increase in defined benefit obligation $ 697.7 $ 735.2  
Maximum [Member] | Actuarial assumption of discount rates [member]      
Disclosure of defined benefit plans [line items]      
Percentage after decrease in discount rate 0.50%    
Minimum [Member] | Actuarial assumption of discount rates [member]      
Disclosure of defined benefit plans [line items]      
Percentage after decrease in discount rate 0.00%