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Capital Surplus and Retained Earnings - Details of Capital Surplus (Detail) $ in Thousands, $ in Thousands | 5 Months Ended | 12 Months Ended
--- | --- | ---
Aug. 06, 2019 TWD ($) | Dec. 31, 2019 TWD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 TWD ($) | Dec. 31, 2017 TWD ($)
Statement [LineItems] |  |  |  |  |
Beginning balance |  | $ 6,263,553 |  |  |
Share-based payments |  | 822 |  | $ 41,043 | $ 123,021
Cash distribution from capital surplus |  |  |  |  | (599,728)
Capital reduction |  |  |  | (1,284,223) | 0
Cancellation of treasury stock | $ 962,503 |  |  |  |
Ending balance |  | 6,050,787 | $ 202,300 | 6,263,553 |
Capital surplus [member] |  |  |  |  |
Statement [LineItems] |  |  |  |  |
Beginning balance |  | 6,263,553 |  | 6,271,448 | 6,888,826
Share-based payments |  | (412) |  | (7,967) | (17,650)
Cash distribution from capital surplus |  |  |  |  | (599,728)
Capital reduction |  |  |  | 72 |
Cancellation of treasury stock |  | (212,354) |  |  |
Ending balance |  | 6,050,787 |  | 6,263,553 | 6,271,448
Share premium [member] | Capital surplus [member] |  |  |  |  |
Statement [LineItems] |  |  |  |  |
Beginning balance |  | 5,873,743 |  | 5,873,743 | 6,473,471
Cash distribution from capital surplus |  |  |  |  | (599,728)
Cancellation of treasury stock |  | (199,501) |  |  |
Ending balance |  | 5,674,242 |  | 5,873,743 | 5,873,743
Employee restricted shares [member] | Capital surplus [member] |  |  |  |  |
Statement [LineItems] |  |  |  |  |
Beginning balance |  | 382,506 |  | 390,401 | 408,051
Share-based payments |  | (412) |  | (7,967) | (17,650)
Capital reduction |  |  |  | 72 |
Cancellation of treasury stock |  | (12,853) |  |  |
Ending balance |  | 369,241 |  | 382,506 | 390,401
Others [member] | Capital surplus [member] |  |  |  |  |
Statement [LineItems] |  |  |  |  |
Beginning balance |  | 7,304 |  | 7,304 | 7,304
Ending balance |  | $ 7,304 |  | $ 7,304 | $ 7,304

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- Definition The amount received or receivable from the issuance of the entity's shares in excess of nominal value and amounts received from other transactions involving the entity's stock or stockholders. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_55&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The decrease in equity resulting from a reduction in issued capital. [Refer: Issued capital] + 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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