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Bonds Payable - Major Terms of Domestic Unsecured Bonds (Detail)
$ in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2022
TWD ($)
Dec. 31, 2022
USD ($)
Bonds payable [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 One Three [member]    
Bonds payable [line items]    
Issuance starting period 2012-10  
Issuance ending period 2022-10  
Coupon Rate 1.53% 1.53%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And One Three [member] | Taiwan [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,400.0  
Domestic Unsecured Bonds Hundred And One Four [member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2013-01  
Issuance ending period 2023-01  
Coupon Rate 1.49% 1.49%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And One Four [member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 3,000.0  
Domestic Unsecured Bonds Hundred And Two One [member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2013-02  
Issuance ending period 2023-02  
Coupon Rate 1.50% 1.50%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Two One [member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 3,600.0  
Domestic Unsecured Bonds Hundred And Two Two [member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2013-07  
Issuance ending period 2023-07  
Coupon Rate 1.70% 1.70%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Two Two [member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 3,500.0  
Domestic Unsecured Bonds Hundred And Two Four [member] | Tranche D [member]    
Bonds payable [line items]    
Issuance starting period 2013-09  
Issuance ending period 2021-03  
Coupon Rate 1.85% 1.85%
Repayment and Interest Payment Bullet repayment; interest payable annually (interest for the six months prior to maturity will accrue on the basis of actual days and be repayable at maturity)  
Domestic Unsecured Bonds Hundred And Two Four [member] | Tranche E [member]    
Bonds payable [line items]    
Issuance starting period 2013-09  
Issuance ending period 2023-03  
Coupon Rate 2.05% 2.05%
Repayment and Interest Payment Bullet repayment; interest payable annually (interest for the six months prior to maturity will accrue on the basis of actual days and be repayable at maturity)  
Domestic Unsecured Bonds Hundred And Two Four [member] | Tranche F [member]    
Bonds payable [line items]    
Issuance starting period 2013-09  
Issuance ending period 2023-09  
Coupon Rate 2.10% 2.10%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Two Four [member] | Taiwan [member] | Tranche D [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 2,600.0  
Domestic Unsecured Bonds Hundred And Two Four [member] | Taiwan [member] | Tranche E [member]    
Bonds payable [line items]    
Domestic unsecured bonds 5,400.0  
Domestic Unsecured Bonds Hundred And Two Four [member] | Taiwan [member] | Tranche F [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 2,600.0  
Domestic Unsecured Bonds Hundred And Nine One [Member]    
Bonds payable [line items]    
Issuance starting period 2020-09  
Issuance ending period 2060-09  
Coupon Rate 2.70% 2.70%
Repayment and Interest Payment Bullet repayment (callable on the 5th anniversary of the issue date and every anniversary thereafter); interest payable annually  
Domestic Unsecured Bonds Hundred And Nine One [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2020-03  
Issuance ending period 2025-03  
Coupon Rate 0.58% 0.58%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine One [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2020-03  
Issuance ending period 2027-03  
Coupon Rate 0.62% 0.62%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine One [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2020-03  
Issuance ending period 2030-03  
Coupon Rate 0.64% 0.64%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine One [Member] | Taiwan [member]    
Bonds payable [line items]    
Domestic unsecured bonds   $ 1,000.0
Domestic Unsecured Bonds Hundred And Nine One [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 3,000.0  
Domestic Unsecured Bonds Hundred And Nine One [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 10,500.0  
Domestic Unsecured Bonds Hundred And Nine One [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 10,500.0  
Domestic Unsecured Bonds Hundred And Nine Two [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2020-04  
Issuance ending period 2025-04  
Coupon Rate 0.52% 0.52%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Two [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2020-04  
Issuance ending period 2027-04  
Coupon Rate 0.58% 0.58%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Two [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2020-04  
Issuance ending period 2030-04  
Coupon Rate 0.60% 0.60%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Two [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 5,900.0  
Domestic Unsecured Bonds Hundred And Nine Two [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 10,400.0  
Domestic Unsecured Bonds Hundred And Nine Two [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 5,300.0  
Domestic Unsecured Bonds Hundred And Nine Three [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2020-05  
Issuance ending period 2025-05  
Coupon Rate 0.55% 0.55%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Three [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2020-05  
Issuance ending period 2027-05  
Coupon Rate 0.60% 0.60%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Three [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2020-05  
Issuance ending period 2030-05  
Coupon Rate 0.64% 0.64%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Three [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,500.0  
Domestic Unsecured Bonds Hundred And Nine Three [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 7,500.0  
Domestic Unsecured Bonds Hundred And Nine Three [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 2,400.0  
Domestic Unsecured Bonds Hundred And Nine Four [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2020-07  
Issuance ending period 2025-07  
Coupon Rate 0.58% 0.58%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Four [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2020-07  
Issuance ending period 2027-07  
Coupon Rate 0.65% 0.65%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Four [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2020-07  
Issuance ending period 2030-07  
Coupon Rate 0.67% 0.67%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Four [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 5,700.0  
Domestic Unsecured Bonds Hundred And Nine Four [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 6,300.0  
Domestic Unsecured Bonds Hundred And Nine Four [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 1,900.0  
Domestic Unsecured Bonds Hundred And Nine Five [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2020-09  
Issuance ending period 2025-09  
Coupon Rate 0.50% 0.50%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Five [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2020-09  
Issuance ending period 2027-09  
Coupon Rate 0.58% 0.58%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Five [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2020-09  
Issuance ending period 2030-09  
Coupon Rate 0.60% 0.60%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Five [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,800.0  
Domestic Unsecured Bonds Hundred And Nine Five [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 8,000.0  
Domestic Unsecured Bonds Hundred And Nine Five [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 2,800.0  
Domestic Unsecured Bonds Hundred And Nine Six Green Bond [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2020-12  
Issuance ending period 2025-12  
Coupon Rate 0.40% 0.40%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Six Green Bond [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2020-12  
Issuance ending period 2027-12  
Coupon Rate 0.44% 0.44%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Six Green Bond [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2020-12  
Issuance ending period 2030-12  
Coupon Rate 0.48% 0.48%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Six Green Bond [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 1,600.0  
Domestic Unsecured Bonds Hundred And Nine Six Green Bond [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 5,600.0  
Domestic Unsecured Bonds Hundred And Nine Six Green Bond [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,800.0  
Domestic Unsecured Bonds Hundred And Nine Seven [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2020-12  
Issuance ending period 2025-12  
Coupon Rate 0.36% 0.36%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Seven [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2020-12  
Issuance ending period 2027-12  
Coupon Rate 0.41% 0.41%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Seven [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2020-12  
Issuance ending period 2030-12  
Coupon Rate 0.45% 0.45%
Repayment and Interest Payment Two equal installments in last two years; interest payable annually  
Domestic Unsecured Bonds Hundred And Nine Seven [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 1,900.0  
Domestic Unsecured Bonds Hundred And Nine Seven [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 10,200.0  
Domestic Unsecured Bonds Hundred And Nine Seven [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 6,400.0  
Domestic Unsecured Bonds Hundred And Ten One [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2021-03  
Issuance ending period 2026-03  
Coupon Rate 0.50% 0.50%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten One [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2021-03  
Issuance ending period 2028-03  
Coupon Rate 0.55% 0.55%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten One [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2021-03  
Issuance ending period 2031-03  
Coupon Rate 0.60% 0.60%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten One [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,800.0  
Domestic Unsecured Bonds Hundred And Ten One [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 11,400.0  
Domestic Unsecured Bonds Hundred And Ten One [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,900.0  
Domestic Unsecured Bonds Hundred And Ten Two [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2021-05  
Issuance ending period 2026-05  
Coupon Rate 0.50% 0.50%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Two [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2021-05  
Issuance ending period 2028-05  
Coupon Rate 0.58% 0.58%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Two [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2021-05  
Issuance ending period 2031-05  
Coupon Rate 0.65% 0.65%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Two [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 5,200.0  
Domestic Unsecured Bonds Hundred And Ten Two [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 8,400.0  
Domestic Unsecured Bonds Hundred And Ten Two [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 5,600.0  
Domestic Unsecured Bonds Hundred And Ten Three [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2021-06  
Issuance ending period 2026-06  
Coupon Rate 0.52% 0.52%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Three [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2021-06  
Issuance ending period 2028-06  
Coupon Rate 0.58% 0.58%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Three [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2021-06  
Issuance ending period 2031-06  
Coupon Rate 0.65% 0.65%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Three [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 6,900.0  
Domestic Unsecured Bonds Hundred And Ten Three [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 7,900.0  
Domestic Unsecured Bonds Hundred And Ten Three [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,900.0  
Domestic Unsecured Bonds Hundred And Ten Four [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2021-08  
Issuance ending period 2025-08  
Coupon Rate 0.485% 0.485%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Four [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2021-08  
Issuance ending period 2026-08  
Coupon Rate 0.50% 0.50%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Four [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2021-08  
Issuance ending period 2028-08  
Coupon Rate 0.55% 0.55%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Four [Member] | Tranche D [member]    
Bonds payable [line items]    
Issuance starting period 2021-08  
Issuance ending period 2031-08  
Coupon Rate 0.62% 0.62%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Four [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,000.0  
Domestic Unsecured Bonds Hundred And Ten Four [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 8,000.0  
Domestic Unsecured Bonds Hundred And Ten Four [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds 5,400.0  
Domestic Unsecured Bonds Hundred And Ten Four [Member] | Taiwan [member] | Tranche D [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 4,200.0  
Domestic Unsecured Bonds Hundred And Ten Six [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2021-10  
Issuance ending period 2026-04  
Coupon Rate 0.535% 0.535%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Six [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2021-10  
Issuance ending period 2026-10  
Coupon Rate 0.54% 0.54%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Six [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2021-10  
Issuance ending period 2028-10  
Coupon Rate 0.60% 0.60%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Six [Member] | Tranche D [member]    
Bonds payable [line items]    
Issuance starting period 2021-10  
Issuance ending period 2031-10  
Coupon Rate 0.62% 0.62%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Six [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 3,200.0  
Domestic Unsecured Bonds Hundred And Ten Six [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 6,900.0  
Domestic Unsecured Bonds Hundred And Ten Six [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds 4,600.0  
Domestic Unsecured Bonds Hundred And Ten Six [Member] | Taiwan [member] | Tranche D [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 1,600.0  
Domestic Unsecured Bonds Hundred And Ten Seven [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2021-12  
Issuance ending period 2026-12  
Coupon Rate 0.65% 0.65%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Seven [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2021-12  
Issuance ending period 2027-06  
Coupon Rate 0.675% 0.675%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Seven [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2021-12  
Issuance ending period 2028-12  
Coupon Rate 0.72% 0.72%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Seven [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 7,700.0  
Domestic Unsecured Bonds Hundred And Ten Seven [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 3,500.0  
Domestic Unsecured Bonds Hundred And Ten Seven [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 5,500.0  
Domestic Unsecured Bonds Hundred And Ten Five [Member]    
Bonds payable [line items]    
Issuance starting period 2021-09  
Issuance ending period 2051-09  
Coupon Rate 3.10% 3.10%
Repayment and Interest Payment Bullet repayment (callable on the 5th anniversary of the issue date and every anniversary thereafter); interest payable annually  
Domestic Unsecured Bonds Hundred And Ten Five [Member] | Taiwan [member]    
Bonds payable [line items]    
Domestic unsecured bonds   $ 1,000.0
Domestic Unsecured Bonds Hundred And Eleven One Green Bond [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2022-01  
Issuance ending period 2027-01  
Coupon Rate 0.63% 0.63%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven One Green Bond [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2022-01  
Issuance ending period 2029-01  
Coupon Rate 0.72% 0.72%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven One Green Bond [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 2,100.0  
Domestic Unsecured Bonds Hundred And Eleven One Green Bond [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 3,300.0  
Domestic Unsecured Bonds Hundred And Eleven Two [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2022-03  
Issuance ending period 2026-09  
Coupon Rate 0.84% 0.84%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Two [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2022-03  
Issuance ending period 2027-03  
Coupon Rate 0.85% 0.85%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Two [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2022-03  
Issuance ending period 2029-03  
Coupon Rate 0.90% 0.90%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Two [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 3,000.0  
Domestic Unsecured Bonds Hundred And Eleven Two [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 9,600.0  
Domestic Unsecured Bonds Hundred And Eleven Two [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 1,600.0  
Domestic Unsecured Bonds Hundred And Eleven Three Green Bond [Member]    
Bonds payable [line items]    
Issuance starting period 2022-05  
Issuance ending period 2027-05  
Coupon Rate 1.50% 1.50%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Three Green Bond [Member] | Taiwan [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 6,100.0  
Domestic Unsecured Bonds Hundred And Eleven Four Green Bond [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2022-07  
Issuance ending period 2026-07  
Coupon Rate 1.60% 1.60%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Four Green Bond [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2022-07  
Issuance ending period 2027-07  
Coupon Rate 1.70% 1.70%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Four Green Bond [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2022-07  
Issuance ending period 2029-07  
Coupon Rate 1.75% 1.75%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Four Green Bond [Member] | Tranche D [member]    
Bonds payable [line items]    
Issuance starting period 2022-07  
Issuance ending period 2032-07  
Coupon Rate 1.95% 1.95%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Four Green Bond [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 1,200.0  
Domestic Unsecured Bonds Hundred And Eleven Four Green Bond [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 10,100.0  
Domestic Unsecured Bonds Hundred And Eleven Four Green Bond [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds 1,200.0  
Domestic Unsecured Bonds Hundred And Eleven Four Green Bond [Member] | Taiwan [member] | Tranche D [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 1,400.0  
Domestic Unsecured Bonds Hundred And Eleven Five [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2022-08  
Issuance ending period 2027-06  
Coupon Rate 1.65% 1.65%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Five [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2022-08  
Issuance ending period 2027-08  
Coupon Rate 1.65% 1.65%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Five [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2022-08  
Issuance ending period 2029-08  
Coupon Rate 1.65% 1.65%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Five [Member] | Tranche D [member]    
Bonds payable [line items]    
Issuance starting period 2022-08  
Issuance ending period 2032-08  
Coupon Rate 1.82% 1.82%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Five [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 2,000.0  
Domestic Unsecured Bonds Hundred And Eleven Five [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 8,900.0  
Domestic Unsecured Bonds Hundred And Eleven Five [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds 2,200.0  
Domestic Unsecured Bonds Hundred And Eleven Five [Member] | Taiwan [member] | Tranche D [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 2,500.0  
Domestic Unsecured Bonds Hundred And Eleven Six Green Bond [Member] | Tranche A [member]    
Bonds payable [line items]    
Issuance starting period 2022-10  
Issuance ending period 2027-10  
Coupon Rate 1.75% 1.75%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Six Green Bond [Member] | Tranche B [member]    
Bonds payable [line items]    
Issuance starting period 2022-10  
Issuance ending period 2029-10  
Coupon Rate 1.80% 1.80%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Six Green Bond [Member] | Tranche C [member]    
Bonds payable [line items]    
Issuance starting period 2022-10  
Issuance ending period 2032-10  
Coupon Rate 2.00% 2.00%
Repayment and Interest Payment Bullet repayment; interest payable annually  
Domestic Unsecured Bonds Hundred And Eleven Six Green Bond [Member] | Taiwan [member] | Tranche A [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 5,700.0  
Domestic Unsecured Bonds Hundred And Eleven Six Green Bond [Member] | Taiwan [member] | Tranche B [member]    
Bonds payable [line items]    
Domestic unsecured bonds 1,000.0  
Domestic Unsecured Bonds Hundred And Eleven Six Green Bond [Member] | Taiwan [member] | Tranche C [member]    
Bonds payable [line items]    
Domestic unsecured bonds $ 3,500.0