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Share-based Payments Arrangement - SENAO's Outstanding Stock Options (Detail) - Senao International Co., Ltd. (SENAO) [Member] | 12 Months Ended
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Dec. 31, 2018 TWD ($) | Dec. 31, 2017 TWD ($) | Dec. 31, 2016 TWD ($)
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |  |
Number of options, Options outstanding at beginning of the year | 5,926,000 | 6,587,000 | 7,787,000
Number of options, Options forfeited | (608,000) | (661,000) | (1,200,000)
Number of options, Options outstanding at end of the year | 5,318,000 | 5,926,000 | 6,587,000
Number of options, Options exercisable at end of the year | 5,318,000 | 5,926,000 | 4,947,000
Weighted-average exercise price, Options outstanding at beginning of the year | $ 70.70 | $ 76.10 | $ 81.40
Weighted-average exercise price, Options outstanding at end of the year | 66.20 | 70.70 | 76.10
Weighted-average exercise price, Options exercisable at end of the year | $ 66.20 | $ 70.70 | $ 76.10

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- Definition The number of share options outstanding in a share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 45 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_45_d&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 45 -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_45_b_i&doctype=Standard -URIDate 2018-03-16 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 45 -Subparagraph b -Clause vi -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_45_b_vi&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition The number of share options exercisable in a share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 45 -Subparagraph b -Clause vii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_45_b_vii&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition The weighted average exercise price of share options exercisable in a share-based payment arrangement. [Refer: Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 45 -Subparagraph b -Clause vii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_45_b_vii&doctype=Standard -URIDate 2018-03-16 + Details
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