Fair Value of Financial Instruments - Summary of Financial Assets And Liabilities Carrying Values By Category And Fair Values (Details) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Detailed Information About Borrowings [Line Items]
Carrying value as per statement of financial position	€ 1,727	€ 1,313	€ 760
Level 1 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	276,748	207,240	273,820
Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	911	568	555
Fair value	213,669	199,084	180,359
Level 3 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	3,229	3,229	3,407
Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Carrying value as per statement of financial position	277,658	207,808	274,375
Carrying value of Assets at fair value through profit and loss	276,748	207,240	273,820
Carrying value loans and receivables	911	568	555
Financial liabilities	216,898	202,313	183,766
Aggregate nominal amount	216,898	202,313	183,766
Loans \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	307	259	219
Loans \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Carrying value as per statement of financial position	307	259	219
Carrying value loans and receivables	307	259	219
Deposits and guarantees \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	396	284	274
Deposits and guarantees \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Carrying value as per statement of financial position	396	284	274
Carrying value loans and receivables	396	284	274
Trade receivables \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	207	25	61
Trade receivables \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Carrying value as per statement of financial position	207	25	61
Carrying value loans and receivables	207	25	61
Cash and cash equivalents \| Level 1 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	276,748	207,240	273,820
Cash and cash equivalents \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Carrying value as per statement of financial position	276,748	207,240	273,820
Carrying value of Assets at fair value through profit and loss	276,748	207,240	273,820
Conditional Advances \| Level 3 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	3,229	3,229	3,407
Conditional Advances \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Financial liabilities	3,229	3,229	3,407
Aggregate nominal amount	3,229	3,229	3,407
Convertible Loans \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	165,454	160,489	155,868
Convertible Loans \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Financial liabilities	165,454	160,489	155,868
Aggregate nominal amount	165,454	160,489	155,868
Bank Loans \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	2,645	3,964	3,488
Bank Loans \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Financial liabilities	2,645	3,964	3,488
Aggregate nominal amount	2,645	3,964	3,488
Obligations under finance leases \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	12,281	1,900	1,890
Obligations under finance leases \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Financial liabilities	12,281	1,900	1,890
Aggregate nominal amount	12,281	1,900	1,890
Accrued Interests \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	1	3	3
Accrued Interests \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Financial liabilities	1	3	3
Aggregate nominal amount	1	3	3
Other Financial Loans and Borrowings \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	7	7	24
Other Financial Loans and Borrowings \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Financial liabilities	7	7	24
Aggregate nominal amount	7	7	24
Trade payables \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	32,753	32,649	19,053
Trade payables \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Financial liabilities	32,753	32,649	19,053
Aggregate nominal amount	32,753	32,649	19,053
Other payables \| Level 2 \| Fair value
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value	527	71	34
Other payables \| Gross
Disclosure Of Detailed Information About Borrowings [Line Items]
Financial liabilities	527	71	34
Aggregate nominal amount	€ 527	€ 71	€ 34

The amount of instruments issued by the entity that represent indebtedness.

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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No definition available.

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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]

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

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The amount of financial assets that are measured at fair value and for which gains (losses) are recognised in profit or loss. A financial asset shall be measured at fair value through profit or loss unless it is measured at amortised cost or at fair value through other comprehensive income. A gain (loss) on a financial asset measured at fair value shall be recognised in profit or loss unless it is part of a hedging relationship, it is an investment in an equity instrument for which the entity has elected to present gains and losses in other comprehensive income or it is a financial asset measured at fair value through other comprehensive income. [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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The amount of financial assets reclassified into the loans and receivables category. [Refer: Loans and receivables; Financial assets]

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