XML 178 R162.htm IDEA: XBRL DOCUMENT v3.21.1
Retirement Benefit Plans - Movements in Defined Benefit Obligation and Fair Value of Plan Assets (Detail)
$ in Millions, $ in Millions
 12 Months Ended
Jul. 01, 2020
TWD ($)
Dec. 31, 2020
TWD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
TWD ($)
Dec. 31, 2018
TWD ($)
Disclosure Of Defined Plan [line items]          
Net defined benefit liability (asset) at beginning of period   $ 1,377   $ 2,370 $ 2,691
Current service cost   2,052   2,927 3,024
Interest expense/interest income   1   10 6
Amounts recognized in profit or loss   2,053   2,937 3,030
Remeasurement on the net defined benefit liability          
Return on plan assets (excluding amounts included in net interest)   (1,308)   (1,338) (875)
Actuarial (gains) losses recognized from changes in demographic assumptions       6 4
Actuarial (gains) losses recognized from changes in financial assumptions   590   647 1,273
Actuarial (gains) losses recognized from experience adjustments   (475)   (842) 813
Amounts recognized in other comprehensive income   (1,193) $ (43) (1,527) 1,215
Contributions from employer   (1,964)   (2,099) (4,374)
Benefits paid   0   0 0
Benefits paid directly by the Company   (263)   (304) (192)
Acquired by business combinations (Note 14) $ 32        
Net defined benefit liability (asset) at end of period   42   1,377 2,370
Present value of funded defined benefit obligation [Member]          
Disclosure Of Defined Plan [line items]          
Net defined benefit liability (asset) at beginning of period   41,197   41,397 37,663
Current service cost   2,052   2,927 3,024
Interest expense/interest income   298   400 550
Amounts recognized in profit or loss   2,350   3,327 3,574
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       6 4
Actuarial (gains) losses recognized from changes in financial assumptions   590   647 1,273
Actuarial (gains) losses recognized from experience adjustments   (475)   (842) 813
Amounts recognized in other comprehensive income   115   (189) 2,090
Contributions from employer   0   0 0
Benefits paid   (3,919)   (3,034) (1,738)
Benefits paid directly by the Company   (263)   (304) (192)
Acquired by business combinations (Note 14) 56        
Net defined benefit liability (asset) at end of period   39,536   41,197 41,397
Fair value of plan assets [Member]          
Disclosure Of Defined Plan [line items]          
Net defined benefit liability (asset) at beginning of period   39,820   39,027 34,972
Current service cost   0   0 0
Interest expense/interest income   297   390 544
Amounts recognized in profit or loss   297   390 544
Remeasurement on the net defined benefit liability          
Return on plan assets (excluding amounts included in net interest)   1,308   1,338 875
Actuarial (gains) losses recognized from changes in demographic assumptions       0 0
Actuarial (gains) losses recognized from changes in financial assumptions   0   0 0
Actuarial (gains) losses recognized from experience adjustments   0   0 0
Amounts recognized in other comprehensive income   1,308   1,338 875
Contributions from employer   1,964   2,099 4,374
Benefits paid   (3,919)   (3,034) (1,738)
Benefits paid directly by the Company   0   0 0
Acquired by business combinations (Note 14) $ 24        
Net defined benefit liability (asset) at end of period   $ 39,494   $ 39,820 $ 39,027