Contents of Significant Accounts - Income Tax - Additional Information (Detail) - TWD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Taxable temporary differences of unrecognized deferred tax liabilities associated with investments in subsidiaries	$ 0	$ 28,072,000
Deductible temporary differences for which no deferred income tax assets have been recognized	$ 445,000	$ 3,727,000

The amount of deductible temporary differences for which no deferred tax asset is recognised in the statement of financial position. [Refer: Temporary differences [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2025-01-01
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-Subparagraph e
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-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
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-IssueDate 2025-01-01
-Paragraph 194
-Subparagraph e
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-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
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-IssueDate 2025-01-01
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-URIDate 2025-03-27

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