Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenue	$ 35,822	$ 25,021	$ 66,341	$ 47,865
Cost of revenue	11,532	7,239	21,192	14,893
Gross profit	24,290	17,782	45,149	32,972
Operating expenses:
Sales and marketing	19,179	11,057	34,955	21,963
Research and development	12,027	5,179	20,198	10,456
General and administrative	8,635	5,065	16,479	10,265
Total operating expenses	39,841	21,301	71,632	42,684
Operating loss	(15,551)	(3,519)	(26,483)	(9,712)
Other income (expense), net:
Interest and investment income	400	77	856	128
Interest expense	(1,572)	(2)	(3,144)	(3)
Other expense, net	(6)	(6)	(204)	(38)
Total other income (expense), net	(1,178)	69	(2,492)	87
Loss before income taxes	(16,729)	(3,450)	(28,975)	(9,625)
Provision for income taxes	(189)	13	(285)	(14)
Net loss	$ (16,918)	$ (3,437)	$ (29,260)	$ (9,639)
Net loss per share attributable to common stockholders:
Basic	$ (0.59)	$ (0.12)	$ (1.02)	$ (0.35)
Diluted	$ (0.59)	$ (0.12)	$ (1.02)	$ (0.35)
Weighted-average common shares outstanding:
Basic	28,848,809	27,877,346	28,642,887	27,526,038
Diluted	28,848,809	27,877,346	28,642,887	27,526,038