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Share-based Payments Arrangement - CHIEF Share-based Compensation Plan (Detail) - CHIEF Telecom Inc. (CHIEF) [Member] | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2017 TWD ($) | Dec. 19, 2017 TWD ($) | Dec. 31, 2016 TWD ($) | Jul. 31, 2016 TWD ($) | Jun. 30, 2016 TWD ($) | Oct. 22, 2015 TWD ($)
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |  |  |  |  |
Exercise Price |  | $ 147.00 |  | $ 34.40 | $ 43.00 | $ 43.00
Grant Date 2015.10.22 [Member] |  |  |  |  |  |
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |  |  |  |  |
Effective Date | 2015.10.22 |  |  |  |  |
Grant Date | 2015.10.22 |  |  |  |  |
Stock Options Units | 2,000 |  |  |  |  |
Exercise Price | $ 34.40 |  | $ 34.40 |  |  |
Original price | $ 43.00 |  |  |  |  |
Grant Date 2017.12.19 [Member] |  |  |  |  |  |
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |  |  |  |  |
Effective Date | 2017.12.18 |  |  |  |  |
Grant Date | 2017.12.19 |  |  |  |  |
Stock Options Units | 950 |  |  |  |  |
Exercise Price | $ 147.00 |  |  |  |  |

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- Definition The date on which share-based payment arrangements are granted. [Refer: Share-based payment arrangements [member]] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 2 -IssueDate 2016-01-13 -Paragraph IG23 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2016-03-30&anchor=para_IG23&doctype=Implementation%20Guidance -URIDate 2016-03-31 + Details
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- Definition The exercise price of outstanding share options. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2016-01-13 -Paragraph 45 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2016-03-30&anchor=para_45_d&doctype=Standard -URIDate 2016-03-31 + Details
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- Definition The number of instruments granted in share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 2 -IssueDate 2016-01-13 -Paragraph IG23 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2016-03-30&anchor=para_IG23&doctype=Implementation%20Guidance -URIDate 2016-03-31 + Details
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- Definition The weighted average share price used as input to the option pricing model to calculate the fair value of share options granted. [Refer: Option pricing model [member]; Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2016-01-13 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2016-03-30&anchor=para_47_a_i&doctype=Standard -URIDate 2016-03-31 + Details
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