Net Loss per Share - EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator (basic and diluted):
Net loss, basic	$ (14,310)	$ (6,529)	$ (28,747)	$ (17,508)
Net loss, diluted	$ (14,310)	$ (6,529)	$ (28,747)	$ (17,508)
Denominator (basic and diluted):
Weighted average common shares outstanding, basic and diluted (in shares)	21,556,646	20,482,032	21,465,772	20,433,564
Net loss per share, basic and diluted (in dollars per share)	$ (0.66)	$ (0.32)	$ (1.34)	$ (0.86)