XML 248 R232.htm IDEA: XBRL DOCUMENT
v3.21.1

Related Parties Transactions - Additional Information (Detail) $ in Millions, $ in Millions | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Aug. 31, 2011 TWD ($) | Dec. 31, 2020 TWD ($) | Dec. 31, 2019 TWD ($) | Dec. 31, 2018 TWD ($) | Aug. 31, 2011 SGD ($)
Disclosure of transactions between related parties [Line Items] |  |  |  |  |
Lease contract value |  | $ 9,597 | $ 9,758 |  |
Lease contract value, prepayment amount |  |  |  | $ 1,551 |
Interest on lease liabilities |  | 80 | 85 | 0 |
ST-2 Satellite Ventures Pte., Ltd. ("STS") [Member] |  |  |  |  |
Disclosure of transactions between related parties [Line Items] |  |  |  |  |
Lease contract value |  | 999 | 1,212 |  |
Interest on lease liabilities |  | $ 9 | $ 11 |  |
ST-2 Satellite Ventures Pte., Ltd. ("STS") [Member] |  |  |  |  |
Disclosure of transactions between related parties [Line Items] |  |  |  |  |
Lease term | 15 years |  |  |  |
Lease contract value | $ 6,000 |  |  |  | $ 261
Lease contract value, prepayment amount | $ 3,068 |  |  |  |
Rental expense |  |  |  | 394 |
Rental expense, offsetting credit of the prepayment |  |  |  | 204 |
Rental expense, additional accrual |  |  |  | $ 190 |

X
- Definition Lease contract for a period. + References No definition available. + Details
Name: | cht_LeaseContractForPeriod
Namespace Prefix: | cht_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Prepaid rent in related parties. + References No definition available. + Details
Name: | cht_PrepaidRentRelatedPartyTransactions
Namespace Prefix: | cht_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Rental expense additional accrual. + References No definition available. + Details
Name: | cht_RentalExpenseAdditionalAccrual
Namespace Prefix: | cht_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Offsetting credit of prepayments on leases. + References No definition available. + Details
Name: | cht_RentalExpenseOffsettingCreditOfPrepayments
Namespace Prefix: | cht_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition The amount of interest expense on lease liabilities. [Refer: Lease liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2020-01-01 -Paragraph 53 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2020-en-r&anchor=para_53_b&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_InterestExpenseOnLeaseLiabilities
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of liabilities related to the entity's leases. Lease is a contract, or part of a contract, that conveys the right to use an underlying asset for a period of time in exchange for consideration. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2020-01-01 -Paragraph 47 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2020-en-r&anchor=para_47_b&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_LeaseLiabilities
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of expense recognised on rental activities. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_85&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_RentalExpense
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | ifrs-full_SignificantInvestmentsInAssociatesAxis=cht_ST2SatelliteVenturesPteLtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CategoriesOfRelatedPartiesAxis=cht_ST2SatelliteVenturesPteLtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |