Reclassifications and restatement of comparative figures (Details) - EUR (€) € / shares in Units, € in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of reclassifications or changes in presentation [line items]
Diluted earnings (loss) per share	€ (1.61)	€ (1.79)	€ (1.70)
Provisions for liabilities and other charges	€ 226	€ 389
Trade and other payables	56,438	47,292
Total income tax payables	10,056	10,882	€ 10,833
Provisions for liabilities and other charges	27,040	19,692
Revenue	160,408	129,058	93,054
Sales and advertising expense	€ 56,019	€ 46,016	€ 36,944
Previously stated
Disclosure of reclassifications or changes in presentation [line items]
Diluted earnings (loss) per share	€ (1.52)	€ (1.68)	€ (1.65)
Trade and other payables		€ 47,681
Total income tax payables		147
Provisions for liabilities and other charges		30,427
Revenue		130,569	€ 94,036
Sales and advertising expense		€ 47,527	€ 37,926
Difference
Disclosure of reclassifications or changes in presentation [line items]
Diluted earnings (loss) per share	€ (0.09)	€ (0.11)	€ (0.05)
Provisions for liabilities and other charges		€ 389
Trade and other payables		(389)
Total income tax payables		10,735
Provisions for liabilities and other charges		(10,735)
Revenue		(1,511)	€ (982)
Sales and advertising expense		€ (1,511)	€ (982)

The amount of current provisions. [Refer: Provisions]

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The amount of current tax for current and prior periods to the extent unpaid. Current tax is the amount of income taxes payable (recoverable) in respect of the taxable profit (tax loss) for a period.

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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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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The amount of non-current provisions. [Refer: Provisions]

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The amount of revenue from contracts with customers. A customer is a party that has contracted with an entity to obtain goods or services that are an output of the entity’s ordinary activities in exchange for consideration.

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The amount of expense relating to the marketing and selling of goods or services.

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The amount of current trade payables and current other payables. [Refer: Current trade payables; Other current payables]

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