Debt - Additional Information (Details) - USD ($)			1 Months Ended	3 Months Ended		9 Months Ended	12 Months Ended
	Feb. 28, 2020	Oct. 27, 2017	Feb. 28, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 04, 2019
Debt Instrument [Line Items]
Unpaid principal amount conversion to shares						$ 50,173,000
Gain on fair value of put option					$ 4,400,000	4,413,000
Net unamortized fees							$ 900,000
Mezzanine Facility | WestRiver
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 10,000,000		$ 10,000,000
Credit facility, maturity date	Mar. 01, 2023
Credit facility, outstanding amount				$ 0		$ 0
Credit facility, interest rate terms						Borrowings under the Mezzanine Facility bear interest at the greater of (i) 10.0% or (ii) the prime rate then in effect plus 5.25%. Interest is calculated on the outstanding principal on a 360-day year basis, payable monthly.
Debt instrument, maturity date	Nov. 06, 2020
Warrants, exercise price per share	$ 9.21		$ 9.21
Warrants expiration date	Mar. 01, 2023		Mar. 01, 2023
Fair value of warrants issued	$ 300,000		$ 300,000
Mezzanine Facility | WestRiver | Minimum
Debt Instrument [Line Items]
Credit facility, weighted-average effective interest rate	10.00%		10.00%
Mezzanine Facility | WestRiver | Maximum
Debt Instrument [Line Items]
Warrants to purchase shares of common stock	99,000		99,000
Revolving Line | A&R Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 20,000,000		$ 20,000,000	$ 10,000,000		$ 10,000,000
Credit facility, increase (decrease) in borrowing capacity	$ 5,000,000
Series 1 Common Stock
Debt Instrument [Line Items]
Repayment of paid principal amount		$ 1,100,000
Unpaid principal amount conversion to shares		$ 18,900,000	$ 35,000,000
Conversion of debt to shares		2,179,360	3,070,174
Initial public offering completion date		Aug. 05, 2020
Silicon Valley Bank | A&R Credit Facility
Debt Instrument [Line Items]
Credit facility, covenant to maintain revenue growth rate of each quarter compared to same quarter in prior year	118.00%
Credit facility, covenant to maintain minimum liquidity ratio	150.00%
Credit facility, covenant terms						We are required to maintain a revenue growth rate of 118% each quarter compared to the same quarter in the prior year. The other covenant requires us to maintain a minimum liquidity ratio of 1.5:1. The liquidity ratio is calculated as unrestricted and unencumbered cash plus sixty percent of net accounts receivable to balance outstanding under the Revolving Line.
Credit facility, covenant compliance						We were in compliance with all covenants as of September 30, 2020.
Silicon Valley Bank | Revolving Line
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		$ 20,000,000							$ 25,000,000
Line of credit facility increase the amended									$ 5,000,000
Credit facility, maturity date		Oct. 27, 2021
Credit facility, weighted-average effective interest rate				3.70%		3.70%	5.60%
Credit facility, outstanding amount				$ 20,000,000		$ 20,000,000	$ 18,500,000
Convertible Term Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Debt principal amount		$ 20,000,000
Weighted average interest rate				5.80%		5.80%		5.60%
Quarterly principal payments		125,000
2020 Convertible Loan
Debt Instrument [Line Items]
Derivative liability				$ 4,400,000		$ 4,400,000
Interest expense				$ 100,000		$ 400,000
2020 Convertible Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Debt principal amount	$ 35,000,000		$ 35,000,000
2018 Term Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		$ 5,000,000
Credit facility, weighted-average effective interest rate				4.30%		4.30%		5.80%
Credit facility, outstanding amount				$ 1,900,000		$ 1,900,000	$ 3,300,000
Credit facility, maturity period		36 months
Converted Within 18 Months
Debt Instrument [Line Items]
Conversion of required minimum return			1.25
Converted Between 18 Months and 24 Months
Debt Instrument [Line Items]
Conversion of required minimum return			1.32
Converted Between 24 Months and Maturity
Debt Instrument [Line Items]
Conversion of required minimum return			1.55
Prime Rate | Mezzanine Facility | WestRiver
Debt Instrument [Line Items]
Variable interest rate	5.25%
Prime Rate | 2018 Term Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Variable interest rate		0.25%
Prime Rate | After January 1, 2020 | Convertible Term Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Variable interest rate		2.00%
Prime Rate | After January 1, 2021 | Convertible Term Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Variable interest rate		4.00%
Prime Rate | After January 1, 2022 | Convertible Term Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Variable interest rate		6.00%
Prime Rate | Prior to January 1, 2022 | 2020 Convertible Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Variable interest rate			4.50%
Prime Rate | From January 1, 2022 and Prior to January 1, 2023 | 2020 Convertible Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Variable interest rate			6.50%
Prime Rate | From January 1, 2023 and Prior to January 1, 2024 | 2020 Convertible Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Variable interest rate			8.50%
Prime Rate | From and After January 1, 2024 | 2020 Convertible Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Variable interest rate			10.50%