Board of Directors - Payments to/DBO for Former Executive Board Members (Details) - Former Executive Board Members - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Payments to/DBO for former executive board members
Payments	€ 1,997	€ 1,667	€ 1,580
DBO December 31	€ 39,993	€ 33,935	€ 32,758

The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan. [Refer: Net defined benefit liability (asset)]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2017-01-01
-Paragraph 141
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_141_g&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_PaymentsFromPlanNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration