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Investment Properties - Key Assumptions and Fair Values of Investment Properties (Detail) $ in Millions, $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 TWD ($) | Dec. 31, 2018 TWD ($) | Dec. 31, 2019 USD ($)
Disclosure of detailed information about investment property [Line Items] |  |  |
Investment properties | $ 8,169 | $ 8,287 | $ 273
Bottom of Range [Member] |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |
Overall capital interest rate | 1.03% | 1.02% |
Profit margin ratio | 12.00% | 12.00% |
Capitalization rate | 0.79% | 0.79% |
Top of Range [Member] |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |
Overall capital interest rate | 4.04% | 4.04% |
Profit margin ratio | 20.00% | 20.00% |
Capitalization rate | 1.74% | 1.75% |
At fair value [Member] |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |
Investment properties | $ 18,701 | $ 18,515 |

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- Definition Investment property capitalization rates. + References No definition available. + Details
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- Definition Profit margin ratio. + References No definition available. + 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 2019-01-01 -Paragraph 76 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2019-en-r&anchor=para_76&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 40 -IssueDate 2019-01-01 -Paragraph 79 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=40&code=ifrs-tx-2019-en-r&anchor=para_79_d&doctype=Standard -URIDate 2019-03-27 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 54 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_54_b&doctype=Standard -URIDate 2019-03-27 + Details
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