Convertible Preferred Stock - Additional Information (Details) $ / shares in Units, $ in Thousands	1 Months Ended		9 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares	Feb. 28, 2019 USD ($) $ / shares shares	Sep. 30, 2020 $ / shares shares	Sep. 30, 2019 USD ($)	Dec. 31, 2019 $ / shares shares
Class Of Stock [Line Items]
Convertible preferred stock, issued | shares			118,766,273		118,766,273
Convertible preferred stock, par value			$ 0.001		$ 0.001
Proceeds from issuance of series H preferred stock | $				$ 10,000
Conversion of stocks, description			The holders of Series A-1, Series A-2, and Series A-3 (collectively, “Series A”); Series B and Series B-1 (collectively, “Combined Series B”); Series C; Series D; Series E; Series F, Series G, and Series H are entitled to convert their shares into common stock at the option of the holder, at any time, into fully paid and non‑assessable shares of common stock. The number of shares of common stock to which a holder of the Series A, Combined Series B, Series C, Series D, Series E, Series F, Series G, and Series H (collectively, “Series Preferred”) can convert is obtained by multiplying the conversion rate that is in effect by the number of shares of Series Preferred being converted. The conversion rate is determined by dividing the original issue price by the applicable conversion price (initially the original issue price for all classes of Series Preferred except Series B‑1, for which the conversion price is initially $2.75). As a result of the reverse stock split effected in October 2020, the conversion rate for the Series Preferred is 0.1684664 per share.  Following the closing of the IPO in October 2020, each share of Series Preferred automatically converted into shares of common stock (based on the then‑effective Series Preferred conversion price).
Preferred stock, voting rights			one vote for each share of common stock on an as‑if‑converted basis.
Preferred stock, redemption terms			Series Preferred stockholders are subject to automatic redemption in the consolidation or merger of the Company or sale of all or substantially all of the Company's assets in which the stockholders of the Company immediately prior to the transaction hold less than 50% of the outstanding securities of the surviving entity.
Maximum
Class Of Stock [Line Items]
Percentage of outstanding share holders required for automatic stock conversion			50.00%
Reverse Stock Split
Class Of Stock [Line Items]
Preferred stock conversion rate			0.1684664
Series H Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, issued | shares	8,695,621	8,695,621	23,923,188
Convertible preferred stock, par value	$ 1.15	$ 1.15	$ 1.15
Proceeds from issuance of series H preferred stock | $	$ 10,000	$ 10,000
Preferred stock dividends rate			8.00%
Series B-1 Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, issued | shares			2,998,852
Convertible preferred stock, par value			$ 3.20
Preferred stock conversion price			$ 2.75
Series G Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, issued | shares			46,146,517
Convertible preferred stock, par value			$ 0.75
Preferred stock dividends rate			8.00%
Series F Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, issued | shares			19,468,203
Convertible preferred stock, par value			$ 1.50
Preferred stock dividends rate			8.00%
Series E Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, issued | shares			7,639,556
Convertible preferred stock, par value			$ 5.00
Preferred stock dividends rate			8.00%
Series D Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, issued | shares			10,874,876
Convertible preferred stock, par value			$ 4.00
Preferred stock dividends rate			8.00%
Series C Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, issued | shares			2,356,596
Convertible preferred stock, par value			$ 3.00
Preferred stock dividends rate			8.00%
Combined Series B
Class Of Stock [Line Items]
Preferred stock dividends rate			8.00%
Series A
Class Of Stock [Line Items]
Preferred stock dividends rate			8.00%