The date on which share-based payment arrangements are effective.

No definition available.

Name:	cht_EffectiveDateOfGrantOfSharebasedPaymentArrangement
Namespace Prefix:	cht_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The date on which share-based payment arrangements are granted. [Refer: Share-based payment arrangements [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph IG23
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_IG23&doctype=Implementation%20Guidance
-URIDate 2019-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph 45
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_45_a&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_DateOfGrantOfSharebasedPaymentArrangement
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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

- Definition

The exercise price of outstanding share options.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph 45
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_45_d&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_ExercisePriceOfOutstandingShareOptions2019
Namespace Prefix:	ifrs-full_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of instruments granted in share-based payment arrangement.

+ References

+ Details

Name:	ifrs-full_NumberOfInstrumentsGrantedInSharebasedPaymentArrangement
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average share price used as input to the option pricing model to calculate the fair value of share options granted. [Refer: Option pricing model [member]; Weighted average [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph 47
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_47_a_i&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019
Namespace Prefix:	ifrs-full_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=cht_SenaoInternationalCoLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Share-based Payment Arrangement - SENAO Share-based Compensation Plan (Detail) - Senao International Co., Ltd. (SENAO) [Member]	12 Months Ended
	Dec. 31, 2019 shares $ / shares	Dec. 31, 2018 $ / shares	Jul. 31, 2018 $ / shares	Jun. 30, 2018 $ / shares	Jul. 31, 2017 $ / shares	Jun. 30, 2017 $ / shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Effective Date	2012.05.28
Grant Date	2013.05.07
Stock Options Units \| shares	10,000,000
Exercise Price	$ 66.20	$ 66.20	$ 66.20	$ 70.70	$ 70.70	$ 76.10
Original price	$ 93.00