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Share-based Payment Arrangements - Summary of Information About New Shares Reserved for Subscription by Employees under Cash Capital Increase Option Plans (Detail) - New shares reserved for subscription by employees under cash capital increase [member] shares in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($) shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Number of options, granted	30,000
Number of options, exercised	25,164
Weighted-average fair value of options granted (NT$ per share) | $	$ 2.80

X

- Definition

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.

+ References

No definition available.

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- Definition

The number of share options exercised in a share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 45
-Subparagraph b
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_b_iv&doctype=Standard
-URIDate 2017-03-09

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- Definition

The number of share options granted in a share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 45
-Subparagraph b
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_b_ii&doctype=Standard
-URIDate 2017-03-09

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- Definition

The weighted average fair value of share options granted during the period at the measurement date. [Refer: Weighted average [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 47
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_47_a&doctype=Standard
-URIDate 2017-03-09

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