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Other reserve - Summary of Other Reserve (Detail) $ in Thousands, $ in Thousands | 12 Months Ended
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Dec. 31, 2019 TWD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 TWD ($) | Dec. 31, 2017 TWD ($)
Disclosure of Other Reserve [Line Items] |  |  |  |
Employee restricted shares - The company |  |  | $ (1,701) |
Disposal of investment in associates | $ 973,609 | $ 32,551 |  | $ 16,929
Foreign currency translation reserve [member] |  |  |  |
Disclosure of Other Reserve [Line Items] |  |  |  |
Beginning balance | 14,516 |  | 65,593 | 10,600
Adjust Balance on Other Reserve |  |  | 65,593 |
Currency translation differences - The company | (104,198) |  | (51,077) | (232,652)
Currency translation differences - Disposal of a subsidiary |  |  |  | 287,645
Ending balance | (89,682) |  | 14,516 | 65,593
Amounts recognized in other comprehensive income (loss) and accumulated in equity relating to non-current assets held for sale [member] |  |  |  |
Disclosure of Other Reserve [Line Items] |  |  |  |
Beginning balance |  |  |  | 287,645
Currency translation differences - Disposal of a subsidiary |  |  |  | (287,645)
Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income [member] |  |  |  |
Disclosure of Other Reserve [Line Items] |  |  |  |
Beginning balance | 106,898 |  |  |
Effect on initial application of IFRS 9 |  |  | 42,843 |
Adjust Balance on Other Reserve |  |  | 42,843 |
Evaluation adjustment - The Company | (52,549) |  | 85,022 |
Evaluation adjustment - Associates | 5,093 |  | (2,438) |
Evaluation adjustment related tax - The Company | 7,016 |  | (18,529) |
Disposal of investment in associates | (72) |  |  |
Ending balance | 66,386 |  | 106,898 |
Unrealized gain on valuation of available -for-sale financial assets [member] |  |  |  |
Disclosure of Other Reserve [Line Items] |  |  |  |
Beginning balance |  |  | 678 |
Effect on initial application of IFRS 9 |  |  | (678) |
Evaluation adjustment - Associates |  |  |  | 678
Ending balance |  |  |  | 678
Unearned employee awards [member] |  |  |  |
Disclosure of Other Reserve [Line Items] |  |  |  |
Beginning balance | (1,701) |  | (54,570) | (200,204)
Effect on initial application of IFRS 9 |  |  | 0 |
Adjust Balance on Other Reserve |  |  | (54,570) |
Employee restricted shares - The company | 1,701 |  | 52,869 | 145,634
Ending balance |  |  | (1,701) | (54,570)
Other reserves [member] |  |  |  |
Disclosure of Other Reserve [Line Items] |  |  |  |
Beginning balance | 119,713 |  | 11,701 | 98,041
Effect on initial application of IFRS 9 |  |  | 42,165 |
Adjust Balance on Other Reserve |  |  | 53,866 |
Currency translation differences - The company | (104,198) |  | (51,077) | (232,652)
Employee restricted shares - The company | 1,701 |  | 52,869 | 145,634
Evaluation adjustment - The Company | (52,549) |  | 85,022 |
Evaluation adjustment - Associates | 5,093 |  | (2,438) | 678
Evaluation adjustment related tax - The Company | 7,016 |  | (18,529) |
Disposal of investment in associates | (72) |  |  |
Ending balance | $ (23,296) |  | $ 119,713 | $ 11,701

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- Definition Adjustments for gain (loss) on disposals investments in subsidiaries, joint ventures and associates to reconcile profit (loss) to net cash flow from (used in) operating activities. [Refer: Associates [member]; Joint ventures [member]; Subsidiaries [member]; Investments in subsidiaries, joint ventures and associates; Profit (loss)] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 7 -IssueDate 2019-01-01 -Paragraph 20 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2019-en-r&anchor=para_20&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The increase (decrease) in equity resulting from the disposal of subsidiaries. [Refer: Subsidiaries [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 106 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_106_d&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition A component of equity representing reserves within equity, not including retained earnings. [Refer: Retained earnings] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 78 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_78_e&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition A component of equity resulting from share-based payments. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 78 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_78_e&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition Adjustment of changes in accounting policy IFRS 9 of other reserves. + References No definition available. + Details
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- Definition Disclosure of other reserve. + References No definition available. + Details
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- Definition Effect on initial application of IFRS 9. + References No definition available. + Details
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- Definition Other reserve adjustment relates to net of tax of company. + References No definition available. + Details
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- Definition Reserve for evaluation adjustment of the associates. + References No definition available. + Details
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- Definition Reserve for evaluation adjustment of the company. + References No definition available. + Details
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- Definition A component of equity representing exchange differences on translation of financial statements of foreign operations recognised in other comprehensive income and accumulated in equity. [Refer: Other comprehensive income] + References No definition available. + Details
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- Details
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