Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued Expenses
Accrued compensation	$ 2,057	$ 1,244
Accrued professional fees	1,502	1,822
Accrued interest expense	264	71
Other	180	88
Total accrued expenses	$ 4,003	$ 3,225