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Short Term Loans - Summary of Short-term Loans (Detail) - Short-term loans [Member] - TWD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Disclosure of detailed information about borrowings [Line Items] |  |
Unsecured bank loans | $ 67 | $ 90
Unsecured loans [Member] | Bottom of Range [Member] |  |
Disclosure of detailed information about borrowings [Line Items] |  |
Interest rates of bank loans | 1.12% | 1.20%
Unsecured loans [Member] | Top of Range [Member] |  |
Disclosure of detailed information about borrowings [Line Items] |  |
Interest rates of bank loans | 2.33% | 2.50%

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- Definition The interest rate on borrowings. [Refer: Borrowings] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 7 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_7&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of loans received from banks that have not been secured by collateral. [Refer: Loans received] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_112_c&doctype=Standard -URIDate 2020-01-01 + Details
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- Details
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- Details
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- Details
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- Details
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