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Related Party Transactions - Summary of Purchases of Materials (Detail) - TWD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
JMC ELECTRONICS CO., LTD. [member] |  |  |
Disclosure of transactions between related parties [Line Items] |  |  |
Purchases of materials | $ 0 | $ 9 | $ 132,494

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- Definition The amount of property and other assets purchased by the entity in related party transactions. [Refer: Related parties [member]] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 24 -IssueDate 2020-01-01 -Paragraph 21 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=24&code=ifrs-tx-2020-en-r&anchor=para_21_b&doctype=Standard -URIDate 2020-01-01 + Details
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- Details
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