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Other Assets - Additional Information (Detail $ in Millions | 12 Months Ended
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Dec. 31, 2019 TWD ($)
Disclosure Of Other Assets [Abstract] |
Impairment loss on other assets | $ 44

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- Definition Disclosure of other assets. + References No definition available. + Details
Name: | cht_DisclosureOfOtherAssetsAbstract
Namespace Prefix: | cht_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Impairment loss recognised in profit or loss other assets. + References No definition available. + Details
Name: | cht_ImpairmentLossRecognisedInProfitOrLossOtherAssets
Namespace Prefix: | cht_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration