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Subsidiaries - Less Than Wholly Owned Subsidiaries of the Company That Have Material Noncontrolling Interests (Detail) $ in Millions, $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 TWD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 TWD ($) | Dec. 31, 2018 TWD ($) | Dec. 31, 2020 USD ($)
Disclosure of subsidiaries [Line Items] |  |  |  |  |
Profit Allocated to Noncontrolling Interests | $ 1,285 | $ 46 | $ 974 | $ 1,024 |
Accumulated Noncontrolling Interests | $ 11,158 |  | $ 10,115 |  | $ 397
Senao International Co., Ltd. (SENAO) [Member] |  |  |  |  |
Disclosure of subsidiaries [Line Items] |  |  |  |  |
Place of Incorporation | Taiwan | Taiwan |  |  |
Principal Place of Business | Taiwan | Taiwan |  |  |
Proportion of Ownership Interests Held by Noncontrolling Interests | 72.00% | 72.00% | 72.00% |  |
Proportion of Voting Rights Held by Noncontrolling Interests | 72.00% | 72.00% | 72.00% |  |
Profit Allocated to Noncontrolling Interests | $ 312 |  | $ 291 | 326 |
Accumulated Noncontrolling Interests | $ 4,189 |  | $ 4,146 |  |
Chunghwa Precision Test Tech. Co., Ltd. (CHPT) [Member] |  |  |  |  |
Disclosure of subsidiaries [Line Items] |  |  |  |  |
Place of Incorporation | Taiwan | Taiwan |  |  |
Principal Place of Business | Taiwan | Taiwan |  |  |
Proportion of Ownership Interests Held by Noncontrolling Interests | 66.00% | 66.00% | 66.00% |  |
Proportion of Voting Rights Held by Noncontrolling Interests | 66.00% | 66.00% | 66.00% |  |
Profit Allocated to Noncontrolling Interests | $ 604 |  | $ 414 | $ 477 |
Accumulated Noncontrolling Interests | 4,606 |  | 4,217 |  |
Individually immaterial subsidiaries with noncontrolling interests [Member] |  |  |  |  |
Disclosure of subsidiaries [Line Items] |  |  |  |  |
Accumulated Noncontrolling Interests | $ 2,363 |  | $ 1,752 |  |

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- Definition The amount of equity in a subsidiary not attributable, directly or indirectly, to a parent. [Refer: Subsidiaries [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph 12 -Subparagraph f -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_12_f&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 54 -Subparagraph q -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_54_q&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 10 -IssueDate 2020-01-01 -Paragraph 22 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=10&code=ifrs-tx-2020-en-r&anchor=para_22&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The profit (loss) from continuing and discontinued operations attributable to non-controlling interests. [Refer: Profit (loss); Non-controlling interests] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph 12 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_12_e&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 81B -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_81B_a_i&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The proportion of the voting rights in a subsidiary held by non-controlling interests. [Refer: Subsidiaries [member]; Non-controlling interests] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph 12 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_12_d&doctype=Standard -URIDate 2020-01-01 + Details
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