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Non-current Financial Assets at Fair Value Through Other Comprehensive Income - Additional Information (Detail) | Dec. 31, 2020 TWD ($)
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Financial assets at fair value through other comprehensive income [abstract] |
Financial assets at fair value through other comprehensive income were pledged | $ 0

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

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- Definition Financial assets at fair value through other comprehensive income pledged. + References No definition available. + Details
Name: | imos_FinancialAssetsAtFairValueThroughOtherComprehensiveIncomePledged
Namespace Prefix: | imos_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant