Profit Before Income Tax - Summary of Operating Expenses Directly Related to Investment Properties (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Direct operating expense from investment property [abstract]
Direct operating expenses of investment properties that generated rental income	$ 465,458	$ 15,704

The amount of direct operating expenses (including repairs and maintenance) arising from investment property that generated rental income during the period recognised in profit or loss. [Refer: Investment property]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 40
-IssueDate 2017-01-01
-Paragraph 75
-Subparagraph f
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=40&date=2017-03-01&anchor=para_75_f_ii&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_DirectOperatingExpenseFromInvestmentPropertyGeneratingRentalIncome
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration