XML 66 R49.htm IDEA: XBRL DOCUMENT
v3.25.1

Contents of Significant Accounts - Investments Accounted For Under the Equity Method - Additional Information (Detail) $ in Thousands, $ in Thousands |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Jan. 06, 2023 shares | Dec. 31, 2024 TWD ($) | Dec. 31, 2024 USD ($) | Dec. 31, 2023 TWD ($) | Dec. 31, 2022 TWD ($) | Dec. 31, 2024 USD ($) | Jul. 31, 2024 TWD ($)
Investments in associates [Line Items] |  |  |  |  |  |  |
Investments accounted for using equity method for which there are published price quotations |  | $ 33,274,869 |  | $ 32,785,800 |  | $ 1,014,787 |
Cash dividends received from investments accounted for under the equity method |  | 1,071,000 |  | 1,870,000 |  |  |
Proceeds from capital reduction of investments accounted for under the equity method |  | 1,601,874 | $ 48,853 | 1,303,106 | $ 0 |  |
Silicon integrated systems corp [Member] |  |  |  |  |  |  |
Investments in associates [Line Items] |  |  |  |  |  |  |
Capital Reduction And Refunded On Investment Accounted For Using Equity Method |  |  |  |  |  |  | $ 499,000
HSUN CHIEH INVESTMENT CO., LTD. (HSUN CHIEH) [member] |  |  |  |  |  |  |
Investments in associates [Line Items] |  |  |  |  |  |  |
Investments accounted for using equity method for which there are published price quotations |  | 4,723,930 |  | 4,126,878 |  |  |
Proceeds from capital reduction of investments accounted for under the equity method |  | 343,000 |  | 343,000 |  |  |
TRIKNIGHT CAPITAL CORPORATION (TRIKNIGHT) [member] |  |  |  |  |  |  |
Investments in associates [Line Items] |  |  |  |  |  |  |
Investments accounted for using equity method for which there are published price quotations |  | 1,298,112 |  | 2,109,906 |  |  |
Proceeds from capital reduction of investments accounted for under the equity method |  | 760,000 |  | 960,000 |  |  |
UNIMICRON TECHNOLOGY CORP. (UNIMICRON) [member] |  |  |  |  |  |  |
Investments in associates [Line Items] |  |  |  |  |  |  |
Investments accounted for using equity method for which there are published price quotations |  | 13,824,584 |  | 13,644,560 |  |  |
UNIMICRON TECHNOLOGY CORP. (UNIMICRON) [member] | SUBTRON TECHNOLOGY CO., LTD. (SUBTRON) [member] |  |  |  |  |  |  |
Investments in associates [Line Items] |  |  |  |  |  |  |
Number of shares exchanged | shares | 23,000,000 |  |  |  |  |  |
Number of shares allotted | shares | 5,000,000 |  |  |  |  |  |
Share exchange description | 1 common share of SUBTRON to exchange 0.219 common shares of UNIMICRON |  |  |  |  |  |
Aggregated individually immaterial associates [member] |  |  |  |  |  |  |
Investments in associates [Line Items] |  |  |  |  |  |  |
Exchange differences arising from translation of the foreign entity |  | 55,000 |  | (3,000) | $ 103,000 |  |
Investments with published price quotations [member] |  |  |  |  |  |  |
Investments in associates [Line Items] |  |  |  |  |  |  |
Investments accounted for using equity method for which there are published price quotations |  | 18,231,000 |  | 18,008,000 |  |  |
Investments with published price quotations [member] | Fair value [member] |  |  |  |  |  |  |
Investments in associates [Line Items] |  |  |  |  |  |  |
Investments accounted for using equity method for which there are published price quotations |  | $ 43,305,000 |  | $ 53,726,000 |  |  |

X
- Definition The gains (losses) recognised in other comprehensive income on exchange differences on the translation of financial statements of foreign operations, net of tax, before reclassification adjustments. [Refer: Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2024-01-01 -Paragraph 91 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_91_a&doctype=Standard -URIDate 2024-03-27 + Details
Name: | ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationNetOfTax
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of investments accounted for using the equity method. The equity method is a method of accounting whereby the investment is initially recognised at cost and adjusted thereafter for the post-acquisition change in the investor's share of net assets of the investee. The investor's profit or loss includes its share of the profit or loss of the investee. The investor's other comprehensive income includes its share of the other comprehensive income of the investee. [Refer: At cost [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2024-01-01 -Paragraph 24 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2024-en-r&anchor=para_24_a&doctype=Standard -URIDate 2024-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2024-01-01 -Paragraph B16 -URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2024-en-r&anchor=para_B16&doctype=Appendix&subtype=B -URIDate 2024-03-27 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2024-01-01 -Paragraph 54 -Subparagraph e -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_54_e&doctype=Standard -URIDate 2024-03-27 + Details
Name: | ifrs-full_InvestmentAccountedForUsingEquityMethod
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Capital reduction and refunded on investment accounted for using equity method. + References No definition available. + Details
Name: | umc_CapitalReductionAndRefundedOnInvestmentAccountedForUsingEquityMethod
Namespace Prefix: | umc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Cash dividends received from investments accounted for under the equity method. + References No definition available. + Details
Name: | umc_CashDividendsReceivedFromInvestmentsAccountedForUnderTheEquityMethod
Namespace Prefix: | umc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investments in associates. + References No definition available. + Details
Name: | umc_InvestmentsInAssociatesLineItems
Namespace Prefix: | umc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of shares allotted. + References No definition available. + Details
Name: | umc_NumberOfSharesAllotted
Namespace Prefix: | umc_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of shares exchanged. + References No definition available. + Details
Name: | umc_NumberOfSharesExchanged
Namespace Prefix: | umc_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Proceeds from capital reduction of investments accounted for under the equity method. + References No definition available. + Details
Name: | umc_ProceedsFromCapitalReductionOfInvestmentsAccountedForUnderTheEquityMethod
Namespace Prefix: | umc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Share exchange description. + References No definition available. + Details
Name: | umc_ShareExchangeDescription
Namespace Prefix: | umc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | umc_FULLSignificantInvestmentsInAssociatesAxis=umc_SiliconIntegratedSystemsCorpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInAssociatesAxis=umc_HsunChiehInvestmentCo.LtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInAssociatesAxis=umc_TriKnightCapitalCorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInAssociatesAxis=umc_UnimicronTechnologyCorpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=umc_SUBTRONTECHNOLOGYCOLTDMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CategoriesOfRelatedPartiesAxis=ifrs-full_AggregatedIndividuallyImmaterialAssociatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfAssetsAxis=umc_InvestmentsWithPublishedPriceQuotationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_MeasurementAxis=ifrs-full_AtFairValueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |