The amount of assets representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognised. [Refer: Business combinations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B67
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B67_d&doctype=Appendix&seq=2
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 134
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_134_a&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 135
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_135_a&doctype=Standard
-URIDate 2017-03-09

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 54
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_c&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_Goodwill
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Goodwill - Summary of Carrying Amount of Goodwill Allocated to Cash-generating Units (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 TWD ($)	Dec. 31, 2014 TWD ($)
Disclosure of information for cash-generating units [line items]
Goodwill	$ 9,934,494	$ 335,172	$ 10,490,309	$ 353,924	$ 10,506,519	$ 10,445,415
Testing segment [member]
Disclosure of information for cash-generating units [line items]
Goodwill	7,775,581	262,334	7,868,961
All other segments [member]
Disclosure of information for cash-generating units [line items]
Goodwill	$ 2,158,913	$ 72,838	$ 2,621,348