Operating Leases - Minimum lease payments under non-cancellable leases are receivable (Details) - EUR (€)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating lease by minimum lease payments receivable under noncancellable operating lease
Total sublease income	€ 625,000	€ 196,000	€ 47,000
Future minimum lease payments under non-cancellable leases are receivable	174,000	463,000	185,000
Less than 1 year
Operating lease by minimum lease payments receivable under noncancellable operating lease
Future minimum lease payments under non-cancellable leases are receivable	€ 174,000	€ 463,000	€ 185,000

The amount of future minimum sublease payments expected to be received under non-cancellable subleases for operating leases. Minimum lease payments are payments over the lease term that the lessee is, or can be, required to make, excluding contingent rent, costs for services and taxes to be paid by, and reimbursed to, the lessor, together with: (a) for a lessee, any amounts guaranteed by the lessee or by a party related to the lessee; or (b) for a lessor, any residual value guaranteed to the lessor by: (i) the lessee; (ii) a party related to the lessee; or (iii) a third party unrelated to the lessor that is financially capable of discharging the obligations under the guarantee.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2019-01-01
-Name IAS
-Number 17
-IssueDate 2017-01-01
-Paragraph 35
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=17&date=2017-03-02&anchor=para_35_b&doctype=Standard&book=B
-URIDate 2017-03-09

Name:	ifrs-full_ExpectedFutureMinimumSubleasePaymentsReceivableUnderNoncancellableSubleasesClassifiedAsOperatingLease
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant