XML 179 R163.htm IDEA: XBRL DOCUMENT
v3.21.1

Retirement Benefit Plans - Pension Costs Recognized in Profit and Loss for Defined Benefit Plans (Detail) - TWD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Disclosure Of Defined Plan [line items] |  |  |
Defined benefit plans pension costs recognized in profit and loss | $ 2,001 | $ 2,859 | $ 2,953
Operating costs [Member] |  |  |
Disclosure Of Defined Plan [line items] |  |  |
Defined benefit plans pension costs recognized in profit and loss | 1,205 | 1,726 | 1,796
Marketing expenses [Member] |  |  |
Disclosure Of Defined Plan [line items] |  |  |
Defined benefit plans pension costs recognized in profit and loss | 603 | 866 | 886
General and administrative expenses [Member] |  |  |
Disclosure Of Defined Plan [line items] |  |  |
Defined benefit plans pension costs recognized in profit and loss | 121 | 164 | 164
Research and development expenses [Member] |  |  |
Disclosure Of Defined Plan [line items] |  |  |
Defined benefit plans pension costs recognized in profit and loss | $ 72 | $ 103 | $ 107

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_DisclosureOfDefinedBenefitPlansLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of post-employment benefit expense relating to defined benefit plans. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2020-01-01 -Paragraph 5 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_5&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_PostemploymentBenefitExpenseDefinedBenefitPlans
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | cht_StatementOfComprehensiveIncomeProfitOrLossLocationAxis=cht_OperatingCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cht_StatementOfComprehensiveIncomeProfitOrLossLocationAxis=cht_MarketingExpensesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cht_StatementOfComprehensiveIncomeProfitOrLossLocationAxis=cht_GeneralAndAdministrativeExpensesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cht_StatementOfComprehensiveIncomeProfitOrLossLocationAxis=cht_ResearchAndDevelopmentExpensesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |