Consolidated Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended										12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014		Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Quarterly Financial Data Details
Service revenue	$ 40,009		$ 37,802	$ 36,121	$ 34,276	$ 32,545		$ 29,737	$ 27,826	$ 26,499	$ 148,208	$ 116,607	$ 94,384
Product revenue	3,521		3,570	3,477	3,637	3,241		3,008	2,989	2,752	14,205	11,990	9,402
Total revenue	43,530		41,372	39,598	37,913	35,786		32,745	30,815	29,251	162,413	128,597	103,786
Operating expenses:
Cost of service revenue	7,655		7,544	7,505	6,997	6,866		5,584	5,209	4,786	29,701	22,445	19,928
Cost of product revenue	4,173		3,959	3,762	3,969	3,999		4,041	3,783	3,347	15,863	15,170	11,801
Research and development	4,348		3,868	3,496	3,406	3,332		3,325	2,640	2,336	15,118	11,633	8,147
Sales and marketing	21,508		20,559	19,440	19,160	18,038		16,051	13,745	13,072	80,667	60,906	45,573
General and administrative	5,794		4,617	3,893	3,878	3,924		5,547	3,125	2,772	18,182	15,368	8,558
Gain on patent sale	0		0	(1,000)	0	0		0	0	0	(1,000)	0	(12,965)
Total operating expenses	43,478		40,547	37,096	37,410	36,159		34,548	28,502	26,313	158,531	125,522	81,042
Income from operations	52		825	2,502	503	(373)		(1,803)	2,313	2,938	3,882	3,075	22,744
Other income, net	210		246	200	177	140		586	1	15
Income from continuing operations before provision for income taxes	262		1,071	2,702	680	(233)		(1,217)	2,314	2,953	4,715	3,817	22,849
Provision (benefit) for income taxes (1)	79	[1]	627	1,411	672	1,738	[1]	(1,306)	826	961	2,789	2,219	9,399
Income from continuing operations	183		444	1,291	8	(1,971)		89	1,488	1,992	1,926	1,598	13,450
Income from discontinued operations, net of income tax provision	0		0	0	0	19		0	154	147	0	320	489
Gain on disposal of discontinued operations, net of income tax provision of $456	0		0	0	0	7		0	589	0	0	596	0
Net income	$ 183		$ 444	$ 1,291	$ 8	$ (1,945)		$ 89	$ 2,231	$ 2,139	$ 1,926	$ 2,514	$ 13,939
Income (loss) per share - continuing operations:
Basic	$ 0.00		$ 0.01	$ 0.01	$ 0.00	$ (0.02)		$ 0.00	$ 0.02	$ 0.03	$ 0.02	$ 0.02	$ 0.19
Diluted	$ 0.00		$ 0.01	$ 0.01	$ 0.00	$ (0.02)		$ 0.00	$ 0.02	$ 0.03	$ 0.02	$ 0.02	$ 0.18
Income per share - discontinued operations:
Basic	$ 0.00		$ 0.00	$ 0.00	$ 0.00	$ 0.00		$ 0.00	$ 0.01	$ 0.00	$ 0.00	$ 0.01	$ 0.01
Diluted	$ 0.00		$ 0.00	$ 0.00	$ 0.00	$ 0.00		$ 0.00	$ 0.01	$ 0.00	$ 0.00	$ 0.01	$ 0.01
Net income (loss) per share:
Basic	$ 0.00		$ 0.01	$ 0.01	$ 0.00	$ (0.02)		$ 0.00	$ 0.03	$ 0.03	$ 0.02	$ 0.03	$ 0.20
Diluted	$ 0.00		$ 0.01	$ 0.01	$ 0.00	$ (0.02)		$ 0.00	$ 0.03	$ 0.03	$ 0.02	$ 0.03	$ 0.19
Shares used in per share calculations:
Basic	88,950		89,594	89,073	88,592	88,184		79,742	72,970	72,510	89,071	78,310	71,390
Diluted	91,266		91,974	91,615	91,445	88,184		83,182	76,232	75,756	91,652	81,658	74,700

[1] Comparability affected by the decrease in fiscal 2015 and increase in fiscal 2014 in the valuation allowance related to the deferred tax asset which resulted in a decrease in fiscal 2015 and an increase in the provision for income taxes of $1.5 million and $1.3 million in the fourth quarter of fiscal 2015 and 2014, respectively.