Term Loan (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Amortization of the debt discount	$ 72
Interest expense	$ 159
Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Warrants outstanding to purchase common stock	50,411
Warrants exercise price per share	$ 2.43
Term Loan [Member]
Debt Instrument [Line Items]
Interest expense	$ 159
Final payment fee	455
Term Loan [Member] | Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Amortization of the debt discount	$ 72
Debt instrument, frequency periodic payment, interest	monthly
Initial Tranche [Member] | Term Loan [Member] | Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Effective interest rate on initial tranche of debt instrument	9.48%	9.25%