Revenue and Expenses - Earnings Per Share (Details) - € / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Analysis of income and expense [abstract]
Basic earnings per share (in euros per share)	€ 0.56	€ 0.42	€ 0.07
Diluted earnings per share (in euros per share)	€ 0.56	€ 0.42	€ 0.07

The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 33
-IssueDate 2017-01-01
-Paragraph 66
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=33&date=2017-03-01&anchor=para_66&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_DilutedEarningsLossPerShare
Namespace Prefix:	ifrs-full_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration