Net 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	$ (8,203)	$ (7,498)	$ (40,892)	$ (35,875)
Denominator:
Weighted-average shares used to compute basic and diluted net loss per share	110,831	104,032	109,147	101,369
Basic and diluted net loss per share	$ (0.07)	$ (0.07)	$ (0.37)	$ (0.35)