Operating lease obligations (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of finance lease and operating lease by lessee [abstract]

Schedule of minimum lease payments under operating leases recognized in the income statement for the year

	Year ended December 31,
	2017		2016		2015
	(Euro, in thousands)
Total minimum lease payments under operating leases	€	4,799	€	4,302	€	4,020