Term Loan - Schedule of Outstanding Loan and Unamortized Debt Discount Balances (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Term loan	$ 15,500
Loan payable, long-term	15,139	$ 15,014
Term Loans[Member]
Debt Instrument [Line Items]
Term loan	15,500	15,500
Less: unamortized discount on loan	(544)	(600)
Accrued portion of final payment fee	183	114
Loan payable, long-term	$ 15,139	$ 15,014

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt discount.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Accrued portion of final payment fee.

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