XML 182 R164.htm IDEA: XBRL DOCUMENT
v3.25.1

Financial Statements Schedule: Valuation and Qualifying Accounts (Detail) - TWD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Allowance for Impairment of property, plant and equipment [member] |  |  |
Disclosure of details of valuation and qualifying accounts [Line Items] |  |  |
January 1 | $ 203,703 | $ 194,467 | $ 183,179
Additions charged to expense or deduction of revenue | 18,618 | 9,236 | 12,721
Deduction/Write-offs/Reversal | (10,061) |  | (1,433)
December 31 | 212,260 | 203,703 | 194,467
Allowance for Impairment of Obsolescence and Decline in Market Value of Inventories [Member] |  |  |
Disclosure of details of valuation and qualifying accounts [Line Items] |  |  |
January 1 | 186,263 | 105,630 | 121,586
Additions charged to expense or deduction of revenue |  | 80,633 |
Deduction/Write-offs/Reversal | (26,114) |  | (15,956)
December 31 | 160,149 | 186,263 | 105,630
Provision for deficiency compensation [member] |  |  |
Disclosure of details of valuation and qualifying accounts [Line Items] |  |  |
January 1 | 33,564 | 26,643 | 4,281
Additions charged to expense or deduction of revenue | 44,297 | 21,495 | 79,827
Deduction/Write-offs/Reversal | (41,937) | (14,574) | (57,465)
December 31 | 35,924 | 33,564 | 26,643
Sales for allowance [member] |  |  |
Disclosure of details of valuation and qualifying accounts [Line Items] |  |  |
January 1 | 37,667 | 37,123 | 9,849
Additions charged to expense or deduction of revenue | 115,150 | 112,488 | 94,641
Deduction/Write-offs/Reversal | (116,421) | (111,944) | (67,367)
December 31 | $ 36,396 | $ 37,667 | $ 37,123

X
- Definition Valuation allowances and reversal. + References No definition available. + Details
Name: | imos_ValuationAllowancesAndReversal
Namespace Prefix: | imos_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Valuation allowances and reversal charged to expense. + References No definition available. + Details
Name: | imos_ValuationAllowancesAndReversalChargedToExpense
Namespace Prefix: | imos_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Valuation allowances and reversal deduction. + References No definition available. + Details
Name: | imos_ValuationAllowancesAndReversalDeduction
Namespace Prefix: | imos_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-X (SX) -Number 210 -Section 12 -Subsection 09 -Paragraph Column E -Publisher SEC Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-X (SX) -Number 210 -Section 12 -Subsection 09 -Paragraph Column D -Publisher SEC Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-X (SX) -Number 210 -Section 12 -Subsection 09 -Paragraph Column C -Subparagraph (1) -Publisher SEC Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-X (SX) -Number 210 -Section 12 -Subsection 09 -Paragraph Column C -Subparagraph (2) -Publisher SEC Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-X (SX) -Number 210 -Section 12 -Subsection 09 -Paragraph Column B -Publisher SEC + Details
Name: | srt_ValuationAndQualifyingAccountsDisclosureLineItems
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | imos_ValuationAllowancesAndReversalTypeAxis=imos_AllowanceForImpairmentOfPlantPropertyAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | imos_ValuationAllowancesAndReversalTypeAxis=imos_AllowanceForImpairmentOfObsolescenceAndDeclineInMarketValueOfInventoriesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | imos_ValuationAllowancesAndReversalTypeAxis=imos_ProvisionForDeficiencyCompensationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | imos_ValuationAllowancesAndReversalTypeAxis=imos_SalesForAllowanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |