Revenue - Schedule of Revenue Recognized in Statements of Profit or Loss (Detail) - EUR (€) € in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disclosure of operating segments [line items]
Revenue from the rendering of services	€ 1,873	€ 18	€ 7,287	€ 46
License income	1,338		1,338
Total revenue	3,211	18	8,625	46
Revenue from external customers (geographical)
Total revenue	3,211	18	8,625	46
Total revenue	3,211	18	8,625	46
North America [member]
Disclosure of operating segments [line items]
Total revenue	3,211	18	8,625	46
Revenue from external customers (geographical)
Total revenue	3,211	18	8,625	46
Total revenue	€ 3,211	€ 18	€ 8,625	€ 46

The income arising in the course of an entity's ordinary activities. Income is increases in economic benefits during the accounting period in the form of inflows or enhancements of assets or decreases of liabilities that result in an increase in equity, other than those relating to contributions from equity participants.

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+ Details