Financial instruments - Effect of derivatives on consolidated financial statements (Details) - EUR (€)	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Disclosure of detailed information about financial instruments [line items]
Interest income recorded as an effect of financial instruments	€ 24,155,000	€ 28,686,000
Interest expense recorded as an effect of financial instruments	€ 104,131,000	€ 121,414,000

The amount of income associated with interest and other financing activities of the entity.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 85
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_85&doctype=Standard
-URIDate 2017-03-09

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration