Percentage of ownership interest in associate.

No definition available.

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- Definition

Percentage of voting power held in associate

+ References

No definition available.

+ Details

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Namespace Prefix:	cht_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

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- Definition

The fair value of investments in associates if there are quoted market prices for the investment. [Refer: Associates [member]; Investments in associates]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2018-01-01
-Paragraph 21
-Subparagraph b
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_21_b_iii&doctype=Standard
-URIDate 2018-03-16

+ Details

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Period Type:	instant

- Definition

The amount of investments in associates accounted for using the equity method. [Refer: Associates [member]; Investments accounted for using equity method]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_55&doctype=Standard
-URIDate 2018-03-16

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Period Type:	instant

- Definition

The entity's share of the other comprehensive income of associates and joint ventures accounted for using the equity method, net of tax. [Refer: Associates [member]; Investments accounted for using equity method; Joint ventures [member]; Other comprehensive income]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective on first application of IFRS 9
-Name IFRS
-Number 4
-IssueDate 2018-01-01
-Paragraph 39M
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=4&date=2018-03-02&anchor=para_39M_b&doctype=Standard&book=b
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2018-01-01
-Paragraph B16
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_B16_c&doctype=Appendix&seq=2
-URIDate 2018-03-16

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 91
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_91_a&doctype=Standard
-URIDate 2018-03-16

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Balance Type:	credit
Period Type:	duration

- Definition

The entity's share of the profit (loss) of associates and joint ventures accounted for using the equity method. [Refer: Associates [member]; Investments accounted for using equity method; Joint ventures [member]; Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2018-01-01
-Paragraph 23
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2018-03-01&anchor=para_23_g&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2018-01-01
-Paragraph 28
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2018-03-01&anchor=para_28_e&doctype=Standard
-URIDate 2018-03-16

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective on first application of IFRS 9
-Name IFRS
-Number 4
-IssueDate 2018-01-01
-Paragraph 39M
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=4&date=2018-03-02&anchor=para_39M_b&doctype=Standard&book=b
-URIDate 2018-03-16

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 82
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_82_c&doctype=Standard
-URIDate 2018-03-16

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- Definition

The entity's share of the total comprehensive income of associates and joint ventures accounted for using the equity method. [Refer: Associates [member]; Joint ventures [member]; Investments accounted for using equity method]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2018-01-01
-Paragraph B16
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_B16_d&doctype=Appendix&seq=2
-URIDate 2018-03-16

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Investments Accounted for Using Equity Method - Investments in Associates (Detail) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018 TWD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 TWD ($)	Dec. 31, 2016 TWD ($)
Disclosure of associates [Line Items]
Investments in associates	$ 2,732		$ 2,326
The Company’s share of profits (loss)	509	$ 17	419	$ 515
Senao Networks, Inc. ("SNI") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 768		$ 704
Percentage of ownership in associates	34.00%		34.00%
Percentage of voting rights in associates	34.00%		34.00%
Fair values based on the closing market prices of SNI	$ 1,447		$ 2,130
ST-2 Satellite Ventures Pte., Ltd. ("STS") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 496		$ 472
Percentage of ownership in associates	38.00%		38.00%
Percentage of voting rights in associates	38.00%		38.00%
International Integrated System, Inc. ("IISI") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 306		$ 292
Percentage of ownership in associates	32.00%		32.00%
Percentage of voting rights in associates	32.00%		32.00%
Viettel-CHT Co., Ltd. ("Viettel-CHT") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 286		$ 256
Percentage of ownership in associates	30.00%		30.00%
Percentage of voting rights in associates	30.00%		30.00%
Taiwan International Standard Electronics Co., Ltd. ("TISE") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 213		$ 132
Percentage of ownership in associates	40.00%		40.00%
Percentage of voting rights in associates	40.00%		40.00%
Chunghwa PChome Fund I Co., Ltd. (“CPFI”) [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 199		$ 0
Percentage of ownership in associates	50.00%		0.00%
Percentage of voting rights in associates	50.00%		0.00%
KKBOX Taiwan Co., Ltd. (“KKBOXTW”) [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 147		$ 140
Percentage of ownership in associates	30.00%		30.00%
Percentage of voting rights in associates	30.00%		30.00%
KingwayTek Technology Co., Ltd. ("KWT") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 97		$ 90
Percentage of ownership in associates	26.00%		26.00%
Percentage of voting rights in associates	26.00%		26.00%
So-net Entertainment Taiwan Limited ("So-net") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 120		$ 104
Percentage of ownership in associates	30.00%		30.00%
Percentage of voting rights in associates	30.00%		30.00%
Taiwan International Ports Logistics Corporation ("TIPL") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 50		$ 50
Percentage of ownership in associates	27.00%		27.00%
Percentage of voting rights in associates	27.00%		27.00%
Click Force Co., Ltd. ("CF") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 38		$ 38
Percentage of ownership in associates	49.00%		49.00%
Percentage of voting rights in associates	49.00%		49.00%
Alliance Digital Tech Co., Ltd. ("ADT") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 3		$ 13
Percentage of ownership in associates	14.00%		14.00%
Percentage of voting rights in associates	14.00%		14.00%
UUPON Inc [member]
Disclosure of associates [Line Items]
Investments in associates	$ 4		$ 12
Percentage of ownership in associates	22.00%		22.00%
Percentage of voting rights in associates	22.00%		22.00%
HopeTech Technologies Limited [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 0		$ 23
Percentage of ownership in associates	0.00%		45.00%
Percentage of voting rights in associates	0.00%		45.00%
Cornerstone Ventures Co., Ltd. (“CVC”) [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 5		$ 0
Percentage of ownership in associates	49.00%		0.00%
Percentage of voting rights in associates	49.00%		0.00%
MeWorks LIMITED (HK) ("MeWorks") [Member]
Disclosure of associates [Line Items]
Investments in associates	$ 0		$ 0
Percentage of ownership in associates	20.00%		20.00%
Percentage of voting rights in associates	20.00%		20.00%
Associates [Member]
Disclosure of associates [Line Items]
The Company’s share of profits (loss)	$ 509		$ 420	557
The Company’s share of other comprehensive income (loss)	5		(4)	(47)
The Company’s share of total comprehensive income (loss)	$ 514		$ 416	$ 510