XML 133 R110.htm IDEA: XBRL DOCUMENT
v3.21.1

Investments accounted for using equity method - Details of Investment in Associates (Detail) - TWD ($) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Apr. 08, 2019 | Dec. 31, 2020 | Dec. 31, 2019
Disclosure of associates [line items] |  |  |
Carrying amount |  | $ 3,271,677 | $ 3,392,910
JMC ELECTRONICS CO., LTD. [member] |  |  |
Disclosure of associates [line items] |  |  |
Carrying amount |  | $ 250,769 | 249,793
Shareholding ratio | 10.00% |  |
Unimos Shanghai [member] |  |  |
Disclosure of associates [line items] |  |  |
Principal place of business |  | Shanghai, PRC |
Measurement method |  | Equity method |
Carrying amount |  | $ 3,020,908 | $ 3,143,117
Shareholding ratio |  | 45.02% | 45.02%
Nature of relationship |  | Strategic Investee |

X
- Definition The country in which an associate of the entity is incorporated. [Refer: Associates [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 27 -IssueDate 2020-01-01 -Paragraph 16 -Subparagraph b -Clause ii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2020-en-r&anchor=para_16_b_ii&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 27 -IssueDate 2020-01-01 -Paragraph 17 -Subparagraph b -Clause ii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2020-en-r&anchor=para_17_b_ii&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph 21 -Subparagraph a -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_21_a_iii&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_CountryOfIncorporationOrResidenceOfAssociate
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The description of the nature of the entity's relationship with an associate (for example, describing the nature of the activities of the associate and whether they are strategic to the entity's activities). [Refer: Associates [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph 21 -Subparagraph a -Clause ii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_21_a_ii&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_DescriptionOfNatureOfEntitysRelationshipWithAssociate
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The description of whether the investment in an associate is measured using the equity method or at fair value. [Refer: At fair value [member]; Associates [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph 21 -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_21_b_i&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_DescriptionOfWhetherInvestmentInAssociateIsMeasuredUsingEquityMethodOrAtFairValue
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfSignificantInvestmentsInAssociatesLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of investments in associates accounted for using the equity method. [Refer: Associates [member]; Investments accounted for using equity method] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_55&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_InvestmentsInAssociatesAccountedForUsingEquityMethod
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The proportion of ownership interest in an associate attributable to the entity. [Refer: Associates [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 27 -IssueDate 2020-01-01 -Paragraph 17 -Subparagraph b -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2020-en-r&anchor=para_17_b_iii&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 27 -IssueDate 2020-01-01 -Paragraph 16 -Subparagraph b -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2020-en-r&anchor=para_16_b_iii&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph 21 -Subparagraph a -Clause iv -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_21_a_iv&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_ProportionOfOwnershipInterestInAssociate
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

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