Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued Expenses
Employee related expenses	$ 3,708	$ 2,480
Intellectual property and patent related fees	2,370	13,251
Process and platform development expenses	2,301	443
Success payment expenses	2,000
Professional service expenses	487	729
Other expenses	183	536
Total	$ 11,049	$ 17,439