Long-Term Debt - Additional Information - Western Alliance LSA (Details) - USD ($)	Jun. 29, 2018	Jun. 13, 2018	Dec. 09, 2016	Mar. 08, 2016	Dec. 31, 2018	Nov. 18, 2018	Aug. 31, 2018	Feb. 28, 2018
Western Alliance LSA
Debt Instrument [Line Items]
Repayment of outstanding term loan	$ 7,000,000
Warrants to purchase, Fair value preferred stock					$ 6.99
Required secure funding		$ 5,000,000						$ 21,000,000
Total cash collected from customers		$ 2,500,000
Prepayment fee					$ 160,000	$ 210,000
Western Alliance LSA | Series D and D-1 Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants to purchase, Fair value preferred stock							$ 20.56
Shares of common stock							11,925
Term Loan | Series D-1 Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants to purchase, Fair value preferred stock							$ 20.56
Shares of common stock							6,814
Term Loan | Western Alliance LSA
Debt Instrument [Line Items]
Proceeds from loan				$ 7,000,000
Term Loan | Western Alliance LSA | Series D and D-1 Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants to purchase shares issued				510,417
Warrants to purchase, Fair value preferred stock				$ 0.48
Term Loan | Western Alliance LSA | Series D Convertible Preferred Stock
Debt Instrument [Line Items]
Debt discount and amortization of interest expense				$ 65,384
Term Loan | Western Alliance LSA | Series D-1 Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants to purchase shares issued			291,667
Debt discount and amortization of interest expense			$ 34,300
Term Loan | Square One Loan And Security Agreement
Debt Instrument [Line Items]
Repayment of outstanding term loan				$ 5,000,000