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Bonds Payable - Summary of Domestic Unsecured Bonds And Overseas Unsecured Bonds (Detail) - TWD ($)
$ in Millions
 4 Months Ended 12 Months Ended
Apr. 20, 2023
Dec. 31, 2022
Disclosure of detailed information about borrowings [line items]    
Repayment and Interest Payment   Bullet repayment (callable at any time, in whole or in part, at the relevant redemption price according to relevant agreements); interest payable semi-annually
Domestic Unsecured Bonds Hundred And Twelve One Green Bond [Member] | Tranche A [member] | Taiwan [member] | Non Adjusting Events After Reporting Period [Member]    
Disclosure of detailed information about borrowings [line items]    
Issuance starting period 2023-03  
Issuance ending period 2028-03  
Domestic unsecured bonds $ 12,200.0  
Coupon Rate 1.54%  
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Twelve One Green Bond [Member] | Tranche B [member] | Taiwan [member] | Non Adjusting Events After Reporting Period [Member]    
Disclosure of detailed information about borrowings [line items]    
Issuance starting period 2023-03  
Issuance ending period 2030-03  
Domestic unsecured bonds $ 2,300.0  
Coupon Rate 1.60%  
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Twelve One Green Bond [Member] | Tranche C [member] | Taiwan [member] | Non Adjusting Events After Reporting Period [Member]    
Disclosure of detailed information about borrowings [line items]    
Issuance starting period 2023-03  
Issuance ending period 2033-03  
Domestic unsecured bonds $ 4,800.0  
Coupon Rate 1.78%  
Repayment and Interest Payment Bullet repayment; interest payable annually