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Lease Arrangements - Summary of Right-of-use Assets (Details) $ in Millions, $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 TWD ($) | Dec. 31, 2019 TWD ($) | Dec. 31, 2018 TWD ($) | Dec. 31, 2020 USD ($)
Disclosure Of Quantitative Information About Rightofuse Assets [Line Items] |  |  |  |
Right-of-use assets | $ 11,009 | $ 11,364 |  | $ 392
Additions to right-of-use assets | 3,796 | 3,803 |  |
Depreciation charge for right-of-use assets |  |  |  |
Depreciation, right-of-use assets | 3,931 | 3,968 | $ 0 |
Handsets Base Stations [Member] |  |  |  |
Disclosure Of Quantitative Information About Rightofuse Assets [Line Items] |  |  |  |
Right-of-use assets | 7,096 | 6,845 |  |
Depreciation charge for right-of-use assets |  |  |  |
Depreciation, right-of-use assets | 2,729 | 2,728 |  |
Others [Member] |  |  |  |
Disclosure Of Quantitative Information About Rightofuse Assets [Line Items] |  |  |  |
Right-of-use assets | 1,708 | 1,916 |  |
Depreciation charge for right-of-use assets |  |  |  |
Depreciation, right-of-use assets | 786 | 821 |  |
Equipment [Member] |  |  |  |
Disclosure Of Quantitative Information About Rightofuse Assets [Line Items] |  |  |  |
Right-of-use assets | 2,205 | 2,603 |  |
Depreciation charge for right-of-use assets |  |  |  |
Depreciation, right-of-use assets | $ 416 | $ 419 |  |

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- Definition The amount of additions to right-of-use assets. [Refer: Right-of-use assets] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2020-01-01 -Paragraph 53 -Subparagraph h -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2020-en-r&anchor=para_53_h&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of depreciation of right-of-use assets. [Refer: Depreciation and amortisation expense; Right-of-use assets] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2020-01-01 -Paragraph 53 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2020-en-r&anchor=para_53_a&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of assets that represent a lessee's right to use an underlying asset for the lease term. Underlying asset is an asset that is the subject of a lease, for which the right to use that asset has been provided by a lessor to a lessee. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2020-01-01 -Paragraph 53 -Subparagraph j -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2020-en-r&anchor=para_53_j&doctype=Standard -URIDate 2020-01-01 + Details
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