Convertible Preferred Stock and Stockholders' Deficit - Schedule of Preferred Stock (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019
Class Of Stock [Line Items]
Preferred Stock Authorized	79,398,350		79,398,350
Preferred Stock Issued	59,398,350		59,398,350
Preferred Stock Outstanding	59,398,350		59,398,350
Carrying Value	$ 173,127		$ 173,127
Liquidation Value	$ 188,034		$ 188,034
Common Stock Issuable Upon Conversion	39,859,139		39,859,139
Series A1 Preferred Stock
Class Of Stock [Line Items]
Preferred Stock Authorized	20,000,000		20,000,000
Series A2 Preferred Stock
Class Of Stock [Line Items]
Preferred Stock Authorized	20,000,000		20,000,000
Preferred Stock Issued	20,000,000		20,000,000
Preferred Stock Outstanding	20,000,000		20,000,000
Carrying Value	$ 29,775		$ 29,775
Liquidation Value	$ 30,000		$ 30,000
Common Stock Issuable Upon Conversion	13,420,970		13,420,970
Series A3 Preferred Stock
Class Of Stock [Line Items]
Preferred Stock Authorized	22,453,987		22,453,987
Preferred Stock Issued	22,453,987		22,453,987
Preferred Stock Outstanding	22,453,987		22,453,987
Carrying Value	$ 19,364		$ 19,364
Liquidation Value	$ 33,681		$ 33,681
Common Stock Issuable Upon Conversion	15,067,706		15,067,706
Series A4 Preferred Stock
Class Of Stock [Line Items]
Preferred Stock Authorized	2,066,666		2,066,666
Preferred Stock Issued	2,066,666		2,066,666
Preferred Stock Outstanding	2,066,666		2,066,666
Carrying Value	$ 3,065		$ 3,065
Liquidation Value	$ 3,100		$ 3,100
Common Stock Issuable Upon Conversion	1,386,831		1,386,831
Series B Preferred Stock
Class Of Stock [Line Items]
Preferred Stock Authorized	14,877,697		14,877,697
Preferred Stock Issued	14,877,697		14,877,697
Preferred Stock Outstanding	14,877,697	14,877,697	14,877,697	14,877,697
Carrying Value	$ 120,923	$ 120,923	$ 120,923	$ 120,923
Liquidation Value	$ 121,253		$ 121,253
Common Stock Issuable Upon Conversion	9,983,632		9,983,632