Other notes - Additional disclosures on financial instruments, comparing carrying amount to fair value of financial assets and liabilities (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, Carrying amount	€ 261,829	€ 271,852
Financial assets, Fair value	261,829	271,852
Financial liabilities, Carrying amount	714,865	742,037
Financial liabilities, Fair value	726,824	754,559
Liabilities measured at amortized cost
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial liabilities, Carrying amount	710,535	741,174
Financial liabilities, Fair value	722,494	753,696
Liabilities measured at amortized cost \| Term loan \| Term Loan
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial liabilities, Carrying amount	558,569	618,059
Financial liabilities, Fair value	570,528	630,581
Liabilities measured at amortized cost \| Term loan \| Local bank loans
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial liabilities, Carrying amount	10,433	0
Financial liabilities, Fair value	10,433	0
Liabilities measured at amortized cost \| Trade payables
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial liabilities, Carrying amount	141,436	122,913
Financial liabilities, Fair value	141,436	122,913
Liabilities measured at amortized cost \| Other financial liabilities
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial liabilities, Carrying amount	97	202
Financial liabilities, Fair value	97	202
Liabilities held for trading \| Derivatives
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial liabilities, Carrying amount	4,330	863
Financial liabilities, Fair value	4,330	863
Loans and receivables
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, Carrying amount	258,865	269,026
Financial assets, Fair value	258,865	269,026
Trade receivables \| Loans and receivables
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, Carrying amount	195,341	190,503
Financial assets, Fair value	195,341	190,503
Loans \| Loans and receivables
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, Carrying amount	574	1,357
Financial assets, Fair value	574	1,357
Miscellaneous financial assets \| Loans and receivables
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, Carrying amount	2,678	3,259
Financial assets, Fair value	2,678	3,259
Cash and cash equivalents \| Loans and receivables
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, Carrying amount	60,272	73,907
Financial assets, Fair value	60,272	73,907
Derivatives \| Financial assets held for trading
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, Carrying amount	2,964	2,826
Financial assets, Fair value	€ 2,964	€ 2,826

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 25
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_25&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35H
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35H&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35I
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35I&doctype=Standard
-URIDate 2017-03-09

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35M
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35M&doctype=Standard
-URIDate 2017-03-09

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35N
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35N&doctype=Standard
-URIDate 2017-03-09

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- Definition

The fair value of financial assets. [Refer: At fair value [member]; Financial assets]

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The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to deliver a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]]

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The fair value of financial liabilities. [Refer: At fair value [member]; Financial liabilities]

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[Line Items] for Disclosure Of Financial Assets And Liabilities [Table]

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