Income Tax - Items for Which No Deferred Income Tax Assets Have Been Recognized (Detail) - TWD ($)	Dec. 31, 2020	Dec. 31, 2019
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	$ 70,000,000	$ 66,000,000
Deductible temporary differences	0	1,000,000
2021 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	12,000,000	13,000,000
2022 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	10,000,000	10,000,000
2023 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	8,000,000	8,000,000
2024 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	8,000,000	8,000,000
2025 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	19,000,000	15,000,000
2026 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	8,000,000	8,000,000
2027 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	3,000,000	3,000,000
2028 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	1,000,000	1,000,000
2029 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	1,000,000	0
2030 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Loss carryforwards	$ 0	$ 0

The amount of deductible temporary differences for which no deferred tax asset is recognised in the statement of financial position. [Refer: Temporary differences [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2020-01-01
-Paragraph 81
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2020-en-r&anchor=para_81_e&doctype=Standard
-URIDate 2020-01-01

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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No definition available.

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The amount of unused tax losses for which no deferred tax asset is recognised in the statement of financial position. [Refer: Unused tax losses [member]]

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