Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenue	$ 44,107,000	$ 33,561,000	$ 86,321,000	$ 65,568,000
Cost of revenue	12,738,000	10,713,000	24,757,000	20,685,000
Gross profit	31,369,000	22,848,000	61,564,000	44,883,000
Operating expenses:
Sales and marketing	17,362,000	13,706,000	33,696,000	26,935,000
Research and development	8,802,000	7,594,000	17,450,000	15,011,000
General and administrative	9,358,000	7,681,000	18,044,000	15,204,000
Total operating expenses	35,522,000	28,981,000	69,190,000	57,150,000
Loss from operations	(4,153,000)	(6,133,000)	(7,626,000)	(12,267,000)
Interest expense, net	(83,000)	(292,000)	(297,000)	(604,000)
Other expense, net	(21,000)	(61,000)	(101,000)	(136,000)
Loss before provision for income taxes	(4,257,000)	(6,486,000)	(8,024,000)	(13,007,000)
Provision for income taxes	118,000	64,000	260,000	137,000
Net loss	$ (4,375,000)	$ (6,550,000)	$ (8,284,000)	$ (13,144,000)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.10)	$ (0.16)	$ (0.20)	$ (0.33)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	43,146,930	39,706,473	41,958,305	39,578,246