Net Loss per Share - Antidilutive securities (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Net Loss per Share and Unaudited Pro Forma Net Loss per Share
Securities excluded from computation of earnings per share amount	3,037,165	19,663,758
Convertible preferred stock
Net Loss per Share and Unaudited Pro Forma Net Loss per Share
Securities excluded from computation of earnings per share amount		18,969,672
Restricted stock awards
Net Loss per Share and Unaudited Pro Forma Net Loss per Share
Securities excluded from computation of earnings per share amount	176,037	295,360
Stock option
Net Loss per Share and Unaudited Pro Forma Net Loss per Share
Securities excluded from computation of earnings per share amount	2,861,128	398,726