Segment information - Revenues of continuing operations (Details) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of geographical areas [line items]
Revenue	€ 127,087	€ 129,519	€ 39,563
Galapagos NV (Belguim)
Disclosure of geographical areas [line items]
Revenue	118,244	121,703	34,082
Galapagos SASU (France)
Disclosure of geographical areas [line items]
Revenue	18	84	25
Fidelta d.o.o. (Croatia)
Disclosure of geographical areas [line items]
Revenue	€ 8,825	€ 7,732	5,440
Xenometrix Inc. (United States)
Disclosure of geographical areas [line items]
Revenue			€ 16

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