Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenue	$ 122,633	$ 125,300	$ 112,287
Cost of revenue	64,352	60,359	52,834
Gross profit	58,281	64,941	59,453
Operating expenses:
Research and development expense	34,168	32,220	25,185
Sales and marketing expense	32,934	31,579	22,330
General and administrative expense	22,299	18,161	12,426
Restructuring costs	3,749
Total operating expenses	93,150	81,960	59,941
Loss from operations	(34,869)	(17,019)	(488)
Other income, net	808	508	616
Interest expense	(1,403)	(908)	(1,633)
Loss before income taxes	(35,464)	(17,419)	(1,505)
Income tax benefit (expense)	233	97	(168)
Net loss	(35,231)	(17,322)	(1,673)
Less: Accretion of preferred stock			(6,258)
Net loss attributable to common stockholders	$ (35,231)	$ (17,322)	$ (7,931)
Net loss per share attributable to common stockholders — basic and diluted	$ (1.65)	$ (0.84)	$ (0.74)
Weighted-average shares outstanding — basic and diluted	21,334	20,680	10,778