Entity Wide Disclosures - Summary of Property and Equipment, Net by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property and equipment, net:
Property and equipment, net	$ 43,805	$ 37,512
U.S.
Property and equipment, net:
Property and equipment, net	34,817	28,152
BELGIUM
Property and equipment, net:
Property and equipment, net	3,672	3,896
Other Europe Countries
Property and equipment, net:
Property and equipment, net	3,764	3,968
Europe [Member]
Property and equipment, net:
Property and equipment, net	7,436	7,864
Other
Property and equipment, net:
Property and equipment, net	$ 1,552	$ 1,496