XML 221 R205.htm IDEA: XBRL DOCUMENT
v3.21.1

Share-based Payments Arrangement - CHIEF's Employee Stock Options Outstanding (Detail) - CHIEF Telecom Inc. (CHIEF) [Member] | 12 Months Ended |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2020 $ / shares | Dec. 31, 2019 $ / shares | Jul. 31, 2020 $ / shares | Jun. 30, 2019 $ / shares | Dec. 31, 2018 $ / shares | Oct. 31, 2018 $ / shares | Aug. 31, 2018 $ / shares | Jun. 30, 2018 $ / shares | Dec. 31, 2017 $ / shares | Dec. 19, 2017 $ / shares
Granted on October 22, 2015 [Member] |  |  |  |  |  |  |  |  |  |
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items] |  |  |  |  |  |  |  |  |  |
Range of Exercise Price | $ 34.40 | $ 34.40 |  |  |  |  |  |  |  |
Number of Options Outstanding | 0 | 314.25 |  |  | 882.75 |  |  |  | 1,936.00 |
Weighted-average Remaining Contractual Life (Years) |  | 9 months 21 days |  |  |  |  |  |  |  |
Weighted-average Exercise Price | $ 0 | $ 34.40 |  |  | $ 34.40 |  |  |  | $ 34.40 |
Options Exercisable Number of Options | 0 | 314.25 |  |  | 416.50 |  |  |  |  |
Option Exercisable Weighted-average Exercise Price | $ 0 | $ 34.40 |  |  | $ 34.40 |  |  |  |  |
Grant Date 2017.12.19 [Member] |  |  |  |  |  |  |  |  |  |
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items] |  |  |  |  |  |  |  |  |  |
Range of Exercise Price | $ 132.70 | $ 135.60 | $ 132.70 | $ 135.60 |  |  | $ 140.60 | $ 144.10 |  | $ 147.00
Number of Options Outstanding | 427.50 | 897.00 |  |  | 925.00 |  |  |  | 950.00 |
Weighted-average Remaining Contractual Life (Years) | 1 year 11 months 15 days | 2 years 11 months 15 days |  |  |  |  |  |  |  |
Weighted-average Exercise Price | $ 132.70 | $ 135.60 |  |  | $ 140.60 |  |  |  | $ 147.00 |
Options Exercisable Number of Options | 213.75 | 448.50 |  |  | 0 |  |  |  |  |
Option Exercisable Weighted-average Exercise Price | $ 132.70 | $ 135.60 |  |  | $ 0 |  |  |  |  |
Granted Date 2018.10.31 [Member] |  |  |  |  |  |  |  |  |  |
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items] |  |  |  |  |  |  |  |  |  |
Range of Exercise Price | $ 138.70 | $ 141.70 | $ 138.70 | $ 141.70 |  | $ 147.00 |  |  |  |
Number of Options Outstanding | 21.00 | 46.00 |  |  | 50.00 |  |  |  | 0 |
Weighted-average Remaining Contractual Life (Years) | 2 years 9 months 29 days | 3 years 9 months 29 days |  |  |  |  |  |  |  |
Weighted-average Exercise Price | $ 138.70 | $ 141.70 |  |  | $ 147.00 |  |  |  | $ 0 |
Options Exercisable Number of Options | 0 | 0 |  |  | 0 |  |  |  |  |
Option Exercisable Weighted-average Exercise Price | $ 0 | $ 0 |  |  | $ 0 |  |  |  |  |
Granted Date 2020.11.13 [Member] |  |  |  |  |  |  |  |  |  |
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items] |  |  |  |  |  |  |  |  |  |
Range of Exercise Price | $ 206.00 |  |  |  |  |  |  |  |  |
Number of Options Outstanding | 200.00 | 0 |  |  |  |  |  |  |  |
Weighted-average Remaining Contractual Life (Years) | 4 years 10 months 13 days |  |  |  |  |  |  |  |  |
Weighted-average Exercise Price | $ 206.00 | $ 0 |  |  |  |  |  |  |  |
Options Exercisable Number of Options | 0 |  |  |  |  |  |  |  |  |
Option Exercisable Weighted-average Exercise Price | $ 0 |  |  |  |  |  |  |  |  |

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

X
- Definition The exercise price of outstanding share options. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_d&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_ExercisePriceOfOutstandingShareOptions2019
Namespace Prefix: | ifrs-full_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of share options outstanding in a share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_d&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_b_i&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph b -Clause vi -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_b_vi&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_NumberOfOutstandingShareOptions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of share options exercisable in a share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph b -Clause vii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_b_vii&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_NumberOfShareOptionsExercisableInSharebasedPaymentArrangement
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition The weighted average exercise price of share options exercisable in a share-based payment arrangement. [Refer: Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph b -Clause vii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_b_vii&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_WeightedAverageExercisePriceOfShareOptionsExercisableInSharebasedPaymentArrangement2019
Namespace Prefix: | ifrs-full_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition The weighted average exercise price of share options outstanding in a share-based payment arrangement. [Refer: Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_b_i&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph b -Clause vi -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_b_vi&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement2019
Namespace Prefix: | ifrs-full_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition The weighted average remaining contractual life of outstanding share options. [Refer: Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_d&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ifrs-full_SignificantInvestmentsInSubsidiariesAxis=cht_CHIEFTelecomIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cht_GrantDateAxis=cht_TwentyTwoOctoberTwoThousandFifteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cht_GrantDateAxis=cht_NineteenDecemberTwoThousandSeventeenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cht_GrantDateAxis=cht_ThirtyOneOctoberTwoThousandEighteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cht_GrantDateAxis=cht_ThirteenNovemberTwoThousandTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |