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Significant Contingent Liabilities and Unrecognized Commitments - Additional Information (Detail) € in Millions, $ in Millions, $ in Millions, $ in Millions | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2024 TWD ($) | Dec. 31, 2023 TWD ($) | Dec. 31, 2024 USD ($) | Dec. 31, 2024 EUR (€) | Dec. 31, 2024 SGD ($) | Dec. 31, 2022 TWD ($) | Aug. 15, 1996 TWD ($)
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |
Unused letters of credit | $ 10 |  |  |  |  |  |
Prepayments | 4,461 | $ 3,330 | $ 136 |  |  |  |
Investment in industry fund | 1,200 |  |  |  |  |  |
Contract liabilities | 16,301 | $ 14,088 | $ 497 |  |  | $ 13,390 |
House and Land Presale Contracts [Member] |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |
House and land presale contracts | 7,704 |  |  |  |  |  |
Contract liabilities | $ 1,064 |  |  |  |  |  |
Next Commercial Bank Co Ltd [Member] |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |
Ownership interest in associates |  | 46.26% |  |  |  |  |
Singapore Telecommunications Limited [Member] |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |
Commitment amount |  |  |  | € 177 | $ 51 |  |
Prepayments | € |  |  |  | € 89 |  |  |
Top of Range [Member] | Next Commercial Bank Co Ltd [Member] |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |
Ownership interest in associates | 25.00% |  |  |  |  |  |
Piping Fund [Member] |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |
Commitment amount |  |  |  |  |  |  | $ 2,000
Commitment to contribute to a Piping Fund, amount contributed |  |  |  |  |  |  | $ 1,000
Commitment to contribute to a Piping Fund, remaining amount | $ 1,000 |  |  |  |  |  |
Property Plant and Equipment [Member] |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |
Commitments for acquisitions of property, plant and equipment | 14,396 |  |  |  |  |  |
Telecommunications [Member] |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |
Acquisitions of telecommunications related inventory | $ 12,366 |  |  |  |  |  |

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