Note 4 - Shareholder Remuneration System - Dividens (Details) - EUR (€) € / shares in Units, € in Millions	1 Months Ended	12 Months Ended
Oct. 31, 2017	Sep. 30, 2017	Jan. 31, 2017	Dec. 31, 2016	Jul. 31, 2016	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share holder Remuneration System Abstract
Dividends Paid per share		€ 0.09		€ 0.08		€ 0.08
Net Dividends Paid per share		€ 0.0729		€ 0.0648		€ 0.0648
Dividend distribution	€ 599		€ 525		€ 517		€ (1,189)	€ (1,535)	€ (1,368)

The amount of dividends paid per ordinary share.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 34
-IssueDate 2016-01-13
-Paragraph 16A
-Subparagraph f
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=34&date=2016-03-30&anchor=para_16A_f&doctype=Standard
-URIDate 2016-03-31

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