Accrued Expenses - Summary of accrued expenses (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Accrued Liabilities, Current [Abstract]
Compensation	[1]	$ 1,943	$ 2,275
Board of directors fees	[2]	15	148
Miscellaneous accruals		301	247
Total accrued expenses		$ 2,259	$ 2,670

[1] The balance of accrued compensation includes normal accruals for commissions, bonuses, paid time off and other accrued payroll items. In addition, three employees, including the Company's Chief Executive Officer ("CEO"), agreed to further defer amounts accrued to them as of December 31, 2017. The Company agreed to further delay and continue to accrue these amounts and increase the balance owed by 1% per month beginning January 1, 2017 to no later than January 31, 2019. As of September 30, 2018, these deferred amounts plus additional 1% accruals owed were paid in full and the balance was $0.

[2] Two members of the Company's board of directors agreed to further defer fees earned from August 2016 to July 2017. The Company agreed to further delay and continue to accrue these amounts and increase the balance owed by 1% per month beginning January 1, 2018 to no later than January 1, 2019. As of September 30, 2018, these deferred amounts plus additional 1% accruals were paid in full and the balance was $0.