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v3.21.1

Investment Properties - Summary of Investment Properties (Detail) $ in Millions, $ in Millions | 12 Months Ended
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Dec. 31, 2020 TWD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 TWD ($) | Dec. 31, 2018 TWD ($)
Disclosure of detailed information about investment property [Line Items] |  |  |  |
Beginning balance | $ 8,169 |  |  |
Depreciation expense | (22) |  | $ (25) | $ (21)
Reversal of impairment loss | 27 | $ 1 | 57 | 19
Ending balance | 9,621 | $ 343 | 8,169 |
Carrying Amount [Member] |  |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |  |
Beginning balance | 9,214 |  | 9,392 | 9,135
Additions | 1,359 |  | 1 | 6
Disposal | (37) |  | (6) |
Reclassification | 126 |  | (173) | 251
Ending balance | 10,662 |  | 9,214 | 9,392
Accumulated depreciation, amortization and impairment [Member] |  |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |  |
Beginning balance | (1,045) |  | (1,105) | (1,087)
Depreciation expense | (22) |  | (25) | (21)
Disposal |  |  | 6 |
Reclassification | (1) |  | 22 | (16)
Reversal of impairment loss | 27 |  | 57 | 19
Ending balance | $ (1,041) |  | $ (1,045) | $ (1,105)

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- Definition The amount of additions to investment property other than those acquired through business combinations. [Refer: Business combinations [member]; Investment property] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2020-01-01 -Paragraph 76 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2020-en-r&anchor=para_76_a&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2020-01-01 -Paragraph 79 -Subparagraph d -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2020-en-r&anchor=para_79_d_i&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of depreciation recognised on investment property. [Refer: Depreciation and amortisation expense; Investment property] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2020-01-01 -Paragraph 79 -Subparagraph d -Clause iv -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2020-en-r&anchor=para_79_d_iv&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2020-01-01 -Paragraph 76 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2020-en-r&anchor=para_76&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of property (land or a building - or part of a building - or both) held (by the owner or by the lessee as a right-of-use asset) to earn rentals or for capital appreciation or both, rather than for: (a) use in the production or supply of goods or services or for administrative purposes; or (b) sale in the ordinary course of business. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2020-01-01 -Paragraph 76 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2020-en-r&anchor=para_76&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2020-01-01 -Paragraph 79 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2020-en-r&anchor=para_79_d&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 54 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_54_b&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of reversal of impairment loss recognised in profit or loss for investment property. [Refer: Reversal of impairment loss recognised in profit or loss; Investment property] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2020-01-01 -Paragraph 76 -Subparagraph g -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2020-en-r&anchor=para_76_g&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2020-01-01 -Paragraph 79 -Subparagraph d -Clause v -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2020-en-r&anchor=para_79_d_v&doctype=Standard -URIDate 2020-01-01 + Details
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