Debt - Carrying Value (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt
Net carrying value of debt, Current Portion	$ 5,993	$ 3,987
Net carrying value of debt, Long-term debt	5,366	8,178
2017 Credit Facility
Debt
Debt, including end of term fee, Current Portion	6,000	4,000
Less: Discount attributable to warrants, end of term fee and debt issuance costs, Current Portion	(17)	(23)
Net carrying value of debt, Current Portion	5,983	3,977
Debt, including end of term fee, Long-term debt	5,720	8,720
Less: Discount attributable to warrants, end of term fee and debt issuance costs, Long-term debt	(369)	(563)
Net carrying value of debt, Long-term debt	5,351	8,157
Debt, including end of term fee, Total	11,720	12,720
Less: Discount attributable to warrants, end of term fee and debt issuance costs, Total	(386)	(586)
Net carrying value of debt, Total	$ 11,334	$ 12,134