Pledged Assets - Assets Pledged as Collaterals (Detail) - TWD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Subclassifications Of Assets Liabilities And Equities [Abstract]
Property, plant and equipment	$ 2,520	$ 2,550
Land held under development (included in inventories)	1,999	1,999
Restricted assets (included in other assets - others)	3	3
Assets pledged as collateral	$ 4,522	$ 4,552

Restricted deposits collateral pledged as security for liabilities.

No definition available.

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Namespace Prefix:	cht_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The fair value of collateral held that is permitted to be sold or repledged in the absence of default by the owner of the collateral. [Refer: At fair value [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 15
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_15_a&doctype=Standard
-URIDate 2018-03-16

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of inventories pledged as security for liabilities. [Refer: Inventories]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 2
-IssueDate 2018-01-01
-Paragraph 36
-Subparagraph h
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=2&date=2018-03-01&anchor=para_36_h&doctype=Standard
-URIDate 2018-03-16

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

The amount of property, plant and equipment pledged as security for liabilities. [Refer: Property, plant and equipment]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 16
-IssueDate 2018-01-01
-Paragraph 74
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=16&date=2018-03-01&anchor=para_74_a&doctype=Standard
-URIDate 2018-03-16

+ Details

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Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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