Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment
Property, plant and equipment, gross	$ 4,374	$ 3,270
Less: Accumulated depreciation	(3,047)	(2,751)
Property, plant and equipment, net	1,327	519
IT equipment
Property, Plant and Equipment
Property, plant and equipment, gross	1,060	642
Laboratory equipment
Property, Plant and Equipment
Property, plant and equipment, gross	3,299	2,613
Other equipment
Property, Plant and Equipment
Property, plant and equipment, gross	$ 15	$ 15