Convertible Preferred Stock - Tabular Disclosure (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)	100,000,000			314,930,070
Convertible preferred stock, shares issued (in shares)	0	0	0	65,428,088	65,428,088	65,428,088
Convertible preferred stock, shares outstanding (in shares)	0			65,428,088
Convertible preferred stock, aggregate liquidation preference	$ 0			$ 106,369
Series A Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)				69,930,070
Convertible preferred stock, shares issued (in shares)				15,384,798
Convertible preferred stock, shares outstanding (in shares)				15,384,798
Convertible preferred stock, aggregate liquidation preference				$ 20,000
Series B Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)				245,000,000
Convertible preferred stock, shares issued (in shares)				50,043,290
Convertible preferred stock, shares outstanding (in shares)				50,043,290
Convertible preferred stock, aggregate liquidation preference				$ 86,369