Net Loss per Share - Computation (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:
Net loss	$ (19,421)	$ (29,174)	$ (39,501)	$ (43,277)
Denominator:
Weighted-average shares used to compute net loss per common share, basic and diluted	32,799,691	24,662,779	30,251,805	24,481,186
Net loss per shares, basic and diluted	$ (0.59)	$ (1.18)	$ (1.31)	$ (1.77)