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Retirement Benefit Plans - Movements in Defined Benefit Obligation and Fair Value of Plan Assets (Detail)
$ in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2023
TWD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2022
TWD ($)
Dec. 31, 2021
TWD ($)
Disclosure Of Defined Plan [line items]        
Net defined benefit liability (asset) at beginning of period $ (2,981)   $ (1,103) $ 42
Current service cost 1,006   1,085 1,253
Loss on settlements 1      
Interest expense/interest income (49)   (10) (5)
Amounts recognized in profit or loss 958   1,075 1,248
Remeasurement on the net defined benefit liability        
Return on plan assets (excluding amounts included in net interest) (309)   (2,968) (501)
Actuarial (gains) losses recognized from changes in demographic assumptions     208 (434)
Actuarial (gains) losses recognized from changes in financial assumptions (100)      
Actuarial (gains) losses recognized from experience adjustments 252   1,606 545
Amounts recognized in other comprehensive income (157) $ (5) (1,154) (390)
Contributions from employer (1,386)   (1,555) (1,727)
Benefits paid 0   0 0
Benefits paid directly by the Company (299)   (244) (276)
Net defined benefit liability (asset) at end of period (3,865)   (2,981) (1,103)
Present value of funded defined benefit obligation [Member]        
Disclosure Of Defined Plan [line items]        
Net defined benefit liability (asset) at beginning of period 33,599   35,502 39,536
Current service cost 1,006   1,085 1,253
Loss on settlements 1      
Interest expense/interest income 403   171 190
Amounts recognized in profit or loss 1,410   1,256 1,443
Remeasurement on the net defined benefit liability        
Return on plan assets (excluding amounts included in net interest) 0   0 0
Actuarial (gains) losses recognized from changes in demographic assumptions     208 (434)
Actuarial (gains) losses recognized from changes in financial assumptions (100)      
Actuarial (gains) losses recognized from experience adjustments 252   1,606 545
Amounts recognized in other comprehensive income 152   1,814 111
Contributions from employer 0   0 0
Benefits paid (4,549)   (4,729) (5,312)
Benefits paid directly by the Company (299)   (244) (276)
Net defined benefit liability (asset) at end of period 30,313   33,599 35,502
Fair value of plan assets [Member]        
Disclosure Of Defined Plan [line items]        
Net defined benefit liability (asset) at beginning of period 36,580   36,605 39,494
Current service cost 0   0 0
Loss on settlements 0      
Interest expense/interest income 452   181 195
Amounts recognized in profit or loss 452   181 195
Remeasurement on the net defined benefit liability        
Return on plan assets (excluding amounts included in net interest) 309   2,968 501
Actuarial (gains) losses recognized from changes in demographic assumptions     0 0
Actuarial (gains) losses recognized from changes in financial assumptions 0      
Actuarial (gains) losses recognized from experience adjustments 0   0 0
Amounts recognized in other comprehensive income 309   2,968 501
Contributions from employer 1,386   1,555 1,727
Benefits paid (4,549)   (4,729) (5,312)
Benefits paid directly by the Company 0   0 0
Net defined benefit liability (asset) at end of period $ 34,178   $ 36,580 $ 36,605