Debt - Long Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Long-term debt
Total long-term debt	$ 23,945	$ 23,718
Maturities of long-term debt
2020	3,656
2021	8,592
2022	8,704
2023	4,756
Term loan
Long-term debt
Term loan payable	25,000	25,000
End of term fee	109
Unamortized debt issuance costs	(1,871)	(1,990)
Total long-term debt	23,238	23,010
Other long-term debt
Long-term debt
Total long-term debt	$ 707	$ 708