Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Net Loss per Share
Net loss attributable to common stockholders	$ (13,089)	$ (12,523)	$ (10,440)	$ (8,210)	$ (2,004)	$ (5,909)	$ (36,052)	$ (16,123)
Weighted-average common shares outstanding, basic and diluted	15,334,241			621,581			11,991,870	586,728
Net loss per share attributable to common stockholders, basic and diluted	$ (0.85)			$ (13.21)			$ (3.01)	$ (27.48)