XML 205 R87.htm IDEA: XBRL DOCUMENT
v3.20.1

Critical Accounting Judgments and Key Sources of Estimation, Uncertainty and Assumption - Additional Information (Detail) | 12 Months Ended
--- | ---
Dec. 31, 2019
Top of Range [Member] |
Disclosure Of Accounting Judgements And Estimates [Line Items] |
Proportion of ownership interest held in some of entities | 50.00%

X
- Definition Disclosure of accounting judgements and estimates. + References No definition available. + Details
Name: | cht_DisclosureOfAccountingJudgementsAndEstimatesLineItems
Namespace Prefix: | cht_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Proportion of ownership interest held in some of entities. + References No definition available. + Details
Name: | cht_ProportionOfOwnershipInterestHeldInSomeOfEntities
Namespace Prefix: | cht_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |