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The amount of dividends paid per ordinary share.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 34
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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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-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_246_f&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
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-URIDate 2025-03-27

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The number of other equity instruments (ie other than share options) granted in a share-based payment arrangement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 2
-IssueDate 2025-01-01
-Paragraph 45
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2025-en-r&anchor=para_45&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2025-01-01
-Paragraph 47
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-URIDate 2025-03-27

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The number of shares authorised.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
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-Paragraph 160
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-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
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-Paragraph 79
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-URIDate 2025-03-27

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The number of shares issued by the entity.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
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-URIDate 2025-03-27

Name:	ifrs-full_NumberOfSharesIssued
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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The nominal value per share.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph B10
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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
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-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-URIDate 2025-03-27

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Percentage of cash dividend on dividend distribution.

No definition available.

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Number of American Depositary Shares issued.

No definition available.

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Data Type:	xbrli:sharesItemType
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Number of common shares represented by ADSs.

No definition available.

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Namespace Prefix:	umc_
Data Type:	xbrli:sharesItemType
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Number of common shares represented by issued American Depositary Shares.

No definition available.

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Data Type:	xbrli:sharesItemType
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The number of other equity instruments (ie other than share options) recalled and cancelled in a share-based payment arrangement.

No definition available.

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Percentage of legal reserve.

No definition available.

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Data Type:	dtr-types:percentItemType
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Period Type:	duration

Percentage of stock dividend on dividend distribution.

No definition available.

Name:	umc_StockDividendPercentageOnDividendDistribution
Namespace Prefix:	umc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

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