Segment information - Revenues by destination (Details) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of geographical areas [line items]
Revenue	€ 288,836	€ 127,087	€ 129,519
United States
Disclosure of geographical areas [line items]
Revenue	117,609	82,050	88,628
Europe
Disclosure of geographical areas [line items]
Revenue	171,113	€ 45,037	40,884
Asia Pacific
Disclosure of geographical areas [line items]
Revenue	€ 114		€ 6

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