Related Party Transactions - Additional Information (Details) - USD ($)			1 Months Ended	2 Months Ended	3 Months Ended		9 Months Ended
	May 08, 2020	Oct. 27, 2017	Jun. 30, 2020	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 18, 2020	Apr. 03, 2020	Mar. 31, 2020	Feb. 29, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Debt discount amortization							$ 1,902,000	$ 1,229,000
Unamortized discount					$ 5,358,000		5,358,000						$ 6,034,000
Interest expense					2,476,000	$ 2,321,000	7,285,000	6,872,000
Change in fair value of derivative liability							(126,000)
Loss on extinguishment of debt							3,401,000
Unsecured Convertible Promissory Note
Related Party Transaction [Line Items]
Debt instrument, maturity date	May 08, 2022
Loan amount	$ 15,000,000
Debt discount amortization			$ 200,000
Debt instrument, annual interest rate	8.00%
Conversion price percentage on IPO price	80.00%
Percentage of premium on aggregate principal amount	50.00%
Derivative liability, fair value	$ 3,600,000				$ 3,800,000		$ 3,800,000
Fair value of common shares issued			3,400,000
Unsecured Convertible Promissory Note | Interest and Other Income (Expense), Net
Related Party Transaction [Line Items]
Change in fair value of derivative liability				$ 200,000
Loss on extinguishment of debt			$ 3,600,000
IPO | Unsecured Convertible Promissory Note
Related Party Transaction [Line Items]
Number of shares on debt conversion			1,250,000
Series B Preferred Stock
Related Party Transaction [Line Items]
Preferred stock, shares issued					0		0			4,444,444		5,066,666	101,867,405
Shares issued, price per share												$ 2.25
Series B Preferred Stock | Unsecured Convertible Promissory Note
Related Party Transaction [Line Items]
Convertible conversion price	$ 13.90
Percentage of price per share	80.00%
Series B Preferred Stock Purchase Warrant | Common Stock | IPO
Related Party Transaction [Line Items]
Warrants exercisable									400,160
2017 Term Loan
Related Party Transaction [Line Items]
Term loan					$ 75,000,000		$ 75,000,000						$ 75,000,000
Credit and Security Agreement and Series B Convertible Preferred Stock Purchase Agreement with Private Equity Firm
Related Party Transaction [Line Items]
Loan amount		$ 75,000,000
Debt discount amortization		$ 9,300,000
Credit and Security Agreement and Series B Convertible Preferred Stock Purchase Agreement with Private Equity Firm | 2017 Term Loan
Related Party Transaction [Line Items]
Debt instrument, interest rate per annum		9.50%
Debt instrument, maturity date							Oct. 27, 2022
Debt instrument, covenant description							The 2017 Term Loan contains customary covenants, including a requirement to maintain a minimum unrestricted cash balance at all times of at least $5.0 million. The Company is in compliance with the 2017 Term Loan covenants. The 2017 Term Loan is secured by all tangible and intangible property and assets of the Company, with the exception of its intellectual property.
Proceeds from term loan		$ 65,700,000
Debt discount amortization					600,000	400,000	$ 1,700,000	1,200,000
Term loan					75,000,000		75,000,000						75,000,000
Unamortized discount					5,400,000		5,400,000						$ 6,000,000
Interest expense					$ 2,400,000	$ 2,200,000	$ 7,100,000	$ 6,600,000
Credit and Security Agreement and Series B Convertible Preferred Stock Purchase Agreement with Private Equity Firm | 2017 Term Loan | Series B Preferred Stock
Related Party Transaction [Line Items]
Proceeds from term loan, preferred stock and preferred stock purchase warrant		124,200,000
Credit and Security Agreement and Series B Convertible Preferred Stock Purchase Agreement with Private Equity Firm | 2017 Term Loan | Minimum
Related Party Transaction [Line Items]
Unrestricted cash		$ 5,000,000
Subscription Agreement with Lender | Series B Preferred Stock
Related Party Transaction [Line Items]
Preferred stock, shares issued											967,130
Shares issued, price per share											$ 2.25