Net Loss Per Share - Summary of Reconciliation of the Denominator Used in the Calculation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net loss	$ (20,923)	$ (11,472)	$ (57,814)	$ (35,878)
Denominator:
Total weighted average common shares outstanding—basic	37,250	34,895	36,585	33,934
Weighted average common shares outstanding-diluted	37,250	34,895	36,585	33,934
Net loss per common share, basic and diluted	$ (0.56)	$ (0.33)	$ (1.58)	$ (1.06)