Financial instruments and risk management (Details) - EUR (€) € in Thousands | Jun. 30, 2018 | Dec. 31, 2017 |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | € 17,461 | € 18,207 |
Financial liabilities | 24,646 | 23,854 |
Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 24,646 | 23,854 |
Financial liabilities, at fair value | 24,806 | 24,288 |
Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | | 0 |
Borrowings | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 14,002 | 5,850 |
Borrowings | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 14,002 | 5,850 |
Financial liabilities, at fair value | 14,162 | 6,284 |
Borrowings | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | | 0 |
Other non-current financial liabilities | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 25 | |
Other non-current financial liabilities | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 25 | |
Financial liabilities, at fair value | 25 | |
Trade payables | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 10,177 | 11,489 |
Trade payables | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 10,177 | 11,489 |
Financial liabilities, at fair value | 10,177 | 11,489 |
Trade payables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | | 0 |
Refund liabilities | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 129 | |
Refund liabilities | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 129 | |
Financial liabilities, at fair value | 129 | |
Other liabilities | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 313 | 6,515 |
Other liabilities | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 313 | 6,515 |
Financial liabilities, at fair value | 313 | 6,515 |
Other liabilities | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | | 0 |
Other current financial liabilities | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 442 | 6,515 |
Other current financial liabilities | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 442 | 6,515 |
Financial liabilities, at fair value | 442 | 6,515 |
Other current financial liabilities | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | | 0 |
Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 17,391 | 18,207 |
Financial assets, at fair value | 17,391 | 18,207 |
Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | 0 |
Deposits | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 21 | 20 |
Deposits | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 21 | 20 |
Financial assets, at fair value | 21 | 20 |
Deposits | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | 0 |
Loan receivables | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 70 | |
Loan receivables | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 0 | |
Financial assets, at fair value | 0 | |
Other receivables | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 3 | 3 |
Other receivables | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 3 | 3 |
Financial assets, at fair value | 3 | 3 |
Other receivables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | 0 |
Other non-current financial assets | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 94 | 23 |
Other non-current financial assets | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 24 | 23 |
Financial assets, at fair value | 24 | 23 |
Other non-current financial assets | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | 0 |
Trade receivables | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 6,589 | 6,814 |
Trade receivables | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 6,589 | 6,814 |
Financial assets, at fair value | 6,589 | 6,814 |
Trade receivables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | 0 |
Deposits | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 2,026 | 2,099 |
Deposits | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 2,026 | 2,099 |
Financial assets, at fair value | 2,026 | 2,099 |
Deposits | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | 0 |
Other receivables | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 699 | 1,057 |
Other receivables | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 699 | 1,057 |
Financial assets, at fair value | 699 | 1,057 |
Other receivables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | 0 |
Other current financial assets | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 2,725 | 3,156 |
Other current financial assets | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 2,725 | 3,156 |
Financial assets, at fair value | 2,725 | 3,156 |
Other current financial assets | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | 0 |
Cash and cash equivalents | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 8,053 | 8,214 |
Cash and cash equivalents | Measured at amortized cost | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 8,053 | 8,214 |
Financial assets, at fair value | 8,053 | 8,214 |
Cash and cash equivalents | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | | € 0 |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Borrowings | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Other non-current financial liabilities | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Trade payables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Refund liabilities | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Other liabilities | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Other current financial liabilities | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial liabilities | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 70 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Deposits | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Loan receivables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 70 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Other receivables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Other non-current financial assets | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 70 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Trade receivables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Deposits | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Other receivables | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Other current financial assets | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | 0 | |
Recurring fair value measurement [member] | Level 3 of fair value hierarchy [member] | Cash and cash equivalents | Measured at fair value | | |
Disclosure of detailed information about financial instruments [line items] | | |
Financial assets | € 0 | |