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Financial Instruments - Foreign Currency Risk Sensitivity Analysis (Detail) - TWD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
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Profit and loss [Member] | Financial instruments [Member] | USD [Member] |  |  |
Disclosure of detailed information about financial instruments [Line Items] |  |  |
Sensitivity analysis due to a 5% increase or decrease in foreign currency exchange | $ 87 | $ 51 | $ 75
Profit and loss [Member] | Financial instruments [Member] | EUR [Member] |  |  |
Disclosure of detailed information about financial instruments [Line Items] |  |  |
Sensitivity analysis due to a 5% increase or decrease in foreign currency exchange | (49) | (30) | (39)
Profit and loss [Member] | Financial instruments [Member] | SGD [Member] |  |  |
Disclosure of detailed information about financial instruments [Line Items] |  |  |
Sensitivity analysis due to a 5% increase or decrease in foreign currency exchange | (33) | (47) | (69)
Profit and loss [Member] | Financial instruments [Member] | RMB [Member] |  |  |
Disclosure of detailed information about financial instruments [Line Items] |  |  |
Sensitivity analysis due to a 5% increase or decrease in foreign currency exchange | 7 | 6 | 0
Profit and loss [Member] | Derivatives [Member] | USD [Member] |  |  |
Disclosure of detailed information about financial instruments [Line Items] |  |  |
Sensitivity analysis due to a 5% increase or decrease in foreign currency exchange | 2 | 0 | 0
Profit and loss [Member] | Derivatives [Member] | EUR [Member] |  |  |
Disclosure of detailed information about financial instruments [Line Items] |  |  |
Sensitivity analysis due to a 5% increase or decrease in foreign currency exchange | 1 | 7 | 3
Equity [Member] | Derivatives [Member] | EUR [Member] |  |  |
Disclosure of detailed information about financial instruments [Line Items] |  |  |
Sensitivity analysis due to a 5% increase or decrease in foreign currency exchange | $ 17 | $ 1 | $ 22

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