Share-Based Payments - Schedule of Breakdown of the Closing Balance BSA 2 (Detail) - BSA 2 [Member]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding	0	0	0	8,049
Exercisable	0	0	0
Exercise price 65 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding	0	0	0
Exercisable	0	0	0

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 45
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_d&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 45
-Subparagraph b
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_b_i&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 45
-Subparagraph b
-Clause vi
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_b_vi&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_NumberOfOutstandingShareOptions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant