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v3.20.1

Non-current Assets Held for Sale and Discontinued Operations - Cumulative Income or Expense Recognized in Other Comprehensive Income Relating to Disposal Group Classified as Held for Sale (Detail) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 TWD ($)
Non-current assets or disposal groups classified as held for sale or as held for distribution to owners [abstract] |
Exchange differences on translation of foreign operations | $ (287,645)

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- References No definition available. + Details
Name: | ifrs-full_NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleOrAsHeldForDistributionToOwnersAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Cumulative income or expense recognised in other comprehensive income relating to non-current assets or disposal groups held for sale. + References No definition available. + Details
Name: | imos_CumulativeIncomeOrExpenseRecognisedInOtherComprehensiveIncomeRelatingToNoncurrentAssetsOrDisposalGroupsHeldForSale
Namespace Prefix: | imos_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration