Financial instruments - Effect of derivatives on consolidated financial statements (Details) - EUR (€)	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure of detailed information about financial instruments [line items]
Interest income recorded as an effect of financial instruments	€ (4,051,000)	€ (5,869,000)	€ 20,104,000	€ 22,817,000
Interest expense recorded as an effect of financial instruments	€ 80,246,000	€ 89,097,000	€ 184,377,000	€ 210,511,000

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

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