Net Loss Per Share - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net loss	$ (10,471)	$ (17,759)	$ (9,040)	$ (10,779)	$ (28,230)	$ (19,819)
Denominator:
Weighted averave common shares used for basic and diluted earnings per share (in shares)	23,482,031		20,448,643		22,969,162	20,407,912
Loss per share:
Basic and diluted (in dollars per share)	$ (0.45)		$ (0.44)		$ (1.23)	$ (0.97)