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Income Tax - Unused Loss Carryforwards and Deductible Temporary Differences for Which No Deferred Income Tax Assets Have Been Recognized (Detail) - TWD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
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Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | $ 73 | $ 47
Deductible temporary differences | 16 | 10
2024 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 0 | 1
2025 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 17 | 15
Investment credits - research and development expenditures | 0 | 8
2026 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 10 | 8
2027 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 3 | 3
2028 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 1 | 1
2029 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 2 | 1
2030 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 1 | 0
2031 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 1 | 0
2032 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 6 | 5
2033 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | 20 | 13
2034 [Member] |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |
Loss carryforwards | $ 12 | $ 0

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- Definition The amount of deductible temporary differences for which no deferred tax asset is recognised in the statement of financial position. [Refer: Temporary differences [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2024-01-01 -Paragraph 81 -Subparagraph e -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=12&code=ifrs-tx-2024-en-r&anchor=para_81_e&doctype=Standard -URIDate 2024-03-27 + Details
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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table. + References No definition available. + Details
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- Definition The amount of unused tax credits for which no deferred tax asset is recognised in the statement of financial position. [Refer: Unused tax credits [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2024-01-01 -Paragraph 81 -Subparagraph e -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=12&code=ifrs-tx-2024-en-r&anchor=para_81_e&doctype=Standard -URIDate 2024-03-27 + Details
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- Definition The amount of unused tax losses for which no deferred tax asset is recognised in the statement of financial position. [Refer: Unused tax losses [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2024-01-01 -Paragraph 81 -Subparagraph e -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=12&code=ifrs-tx-2024-en-r&anchor=para_81_e&doctype=Standard -URIDate 2024-03-27 + Details
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