Accounting judgments and estimates (Details) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting judgments and estimates
Intangible assets other than goodwill	€ 14,145	€ 8,795
Volatility	70.00%	70.00%	60.00%
Gross carrying amount
Accounting judgments and estimates
Intangible assets other than goodwill	€ 21,534	€ 13,868	€ 10,809
Gross carrying amount \| Capitalized development costs
Accounting judgments and estimates
Intangible assets other than goodwill	€ 14,145	€ 8,795

The expected volatility of the share price used to calculate the fair value of the share options granted. Expected volatility is a measure of the amount by which a price is expected to fluctuate during a period. The measure of volatility used in option pricing models is the annualised standard deviation of the continuously compounded rates of return on the share over a period of time.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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 identifiable non-monetary assets without physical substance. This amount does not include goodwill. [Refer: Goodwill]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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