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Term Loan (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Aug. 31, 2018
Debt Instrument [Line Items]
Interest expense	$ 358	$ 159
Term Loan [Member]
Debt Instrument [Line Items]
Interest expense	358	159
Final payment fee	1,008
Silicon Valley Bank [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Amortization of debt discount and accretion of final payment fee	$ 125	$ 72
Debt instrument, frequency periodic payment, interest	monthly
Silicon Valley Bank [Member] \| Term Loan [Member] \| Loan Agreement [Member]
Debt Instrument [Line Items]
Aggregate principal amount of debt instrument				$ 15,500
Warrants outstanding to purchase common stock	40,000
Warrants exercise price per common share	$ 9.79
Silicon Valley Bank [Member] \| Term Loan [Member] \| Loan Agreement [Member] \| Initial Tranche [Member]
Debt Instrument [Line Items]
Effective interest rate on initial tranche of debt instrument	9.53%		9.53%