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Retirement Benefit Plans - Additional Information (Detail) - TWD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Disclosure of defined benefit plans [line items]      
Employer contribution percentage, defined contribution plans 6.00%    
Defined contribution plans expense $ 3,711.0 $ 2,809.5 $ 2,609.7
Employer contribution percentage, defined benefit plans 2.00%    
Defined benefit plans contribution in the next year $ 2,269.9    
Weighted average duration of the defined benefit obligation 9 years    
Future salary increase rate (2021) 3.00% 3.00%  
Forecast [Member]      
Disclosure of defined benefit plans [line items]      
Future salary increase rate (2021) 20.00%    
Actuarial assumption of discount rates [member]      
Disclosure of defined benefit plans [line items]      
Amount of increase in defined benefit obligation $ 780.5 $ 694.7  
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 $ 759.5 $ 836.0  
Maximum [Member] | Actuarial assumption of expected rates of salary increases [member]      
Disclosure of defined benefit plans [line items]      
Percentage of increase in salary 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%