Income Tax - Reconciliation of Accounting Profit and Income Tax Expense (Parenthetical) (Detail)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation Of Accounting Profit Multiplied By Applicable Tax Rates [Abstract]
Statutory rate	20.00%	17.00%	17.00%

The applicable income tax rate.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2018-01-01
-Paragraph 81
-Subparagraph c
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_81_c_ii&doctype=Standard
-URIDate 2018-03-16

Name:	ifrs-full_ApplicableTaxRate
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration