Consolidated Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Quarterly Financial Data Details
Service revenue	$ 62,654	$ 60,149	$ 57,717	$ 55,296	$ 52,174	$ 48,948	$ 46,951	$ 44,168	$ 235,816	$ 192,241	$ 148,208
Product revenue	3,834	3,527	5,466	4,745	5,160	4,220	3,991	3,724	17,572	17,095	14,205
Total revenue	66,488	63,676	63,183	60,041	57,334	53,168	50,942	47,892	253,388	209,336	162,413
Operating expenses:
Cost of service revenue	10,803	10,525	10,837	10,235	9,720	9,713	9,186	8,459	42,400	37,078	29,701
Cost of product revenue	4,187	4,240	5,782	5,505	6,103	5,087	4,596	4,382	19,714	20,168	15,863
Research and development	7,142	7,095	6,505	6,710	6,110	6,404	6,446	5,080	27,452	24,040	15,118
Sales and marketing	38,228	35,667	33,691	31,691	31,240	27,585	26,730	23,824	139,277	109,379	80,667
General and administrative	9,814	7,852	6,747	6,801	7,132	6,888	5,657	6,068	31,214	25,745	18,182
Total operating expenses	70,174	65,379	63,562	60,942	60,305	55,677	52,615	47,813	260,057	216,410	158,531
Income (loss) from operations	(3,686)	(1,703)	(379)	(901)	(2,971)	(2,509)	(1,673)	79	(6,669)	(7,074)	3,882
Other income, net	583	408	391	410	397	272	204	234	1,792	1,107	833
Income (loss) before provision (benefit) for income taxes	(3,103)	(1,295)	12	(491)	(2,574)	(2,237)	(1,469)	313	(4,877)	(5,967)	4,715
Provision (benefit) for income taxes	(178)	30	(15)	37	(1,498)	(557)	423	785	(126)	(847)	2,789
Net income (loss)	$ (2,925)	$ (1,325)	$ 27	$ (528)	$ (1,076)	$ (1,680)	$ (1,892)	$ (472)	$ (4,751)	$ (5,120)	$ 1,926
Net income (loss) per share:
Basic	$ (0.03)	$ (0.01)	$ 0.00	$ (0.01)	$ (0.01)	$ (0.02)	$ (0.02)	$ (0.01)	$ (0.05)	$ (0.06)	$ 0.02
Diluted	$ (0.03)	$ (0.01)	$ 0.00	$ (0.01)	$ (0.01)	$ (0.02)	$ (0.02)	$ (0.01)	$ (0.05)	$ (0.06)	$ 0.02
Shares used in per share calculations:
Basic	91,175	90,774	89,987	89,434	88,888	88,289	88,557	88,233	90,340	88,477	89,071
Diluted	91,175	90,774	93,447	89,434	88,888	88,289	88,557	88,233	90,340	88,477	91,652