Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment
Property, plant and equipment, gross	$ 4,595	$ 4,374
Less: Accumulated depreciation	(3,456)	(3,047)
Property, plant and equipment, net	1,139	1,327
IT equipment
Property, Plant and Equipment
Property, plant and equipment, gross	1,079	1,060
Laboratory equipment
Property, Plant and Equipment
Property, plant and equipment, gross	3,392	3,299
Other equipment
Property, Plant and Equipment
Property, plant and equipment, gross	$ 124	$ 15