Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Revenue	$ 18,603	$ 12,335	$ 46,828	$ 35,461
Operating expenses:
Cost of revenue	6,367	5,618	18,947	15,322
Research and development	4,006	3,563	11,734	9,453
Selling and marketing	7,087	6,048	22,416	18,606
General and administrative	5,763	5,728	18,062	17,062
Intangible asset amortization	266	266	800	533
Total operating expenses	23,489	21,223	71,959	60,976
Loss from operations	(4,886)	(8,888)	(25,131)	(25,515)
Interest expense	(799)	(92)	(1,951)	(269)
Other income, net	48	35	127	93
Net loss	(5,637)	(8,945)	(26,955)	(25,691)
Comprehensive loss	$ (5,637)	$ (8,945)	$ (26,955)	$ (25,691)
Net loss per common share, basic and diluted (in usd per share)	$ (0.20)	$ (0.32)	$ (0.97)	$ (1.01)
Shares used to compute net loss per common share, basic and diluted	27,916,819	27,640,806	27,865,100	25,428,506