Deferred tax (Tables)

12 Months Ended

Dec. 31, 2017

Deferred tax assets and liabilities [abstract]

Schedule of deferred tax

	December 31,
	2017		2016		2015
	(Euro, in thousands)
Recognized deferred tax assets and liabilities
Assets	€	1,978	€	1,957	€	1,726
Liabilities	€	—	€	—	€	—
Deferred tax assets unrecognized	€	164,079	€	128,377	€	145,513
Deferred taxes in the consolidated statement of operations	€	20	€	231	€	1,433
Tax benefit arising from previously unrecognized tax assets used to reduce deferred tax expense (+)		414		421		1,433
Deferred tax expenses relating to change in tax rates		(181)
Deferred tax expenses relating to use of previously recognized deferred tax assets		(213)		(190)