Accrued Expenses and Long-term Liabilities - Schedule of Long Term Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Warrant liability	$ 358	$ 361
Uncertain tax positions	3,895	3,838
Other		120
Total other long-term liabilities	$ 4,253	$ 4,319