Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Revenue:
Product	$ 272,895	$ 234,268	$ 198,749
Service	180,774	162,379	151,801
Total revenue	453,669	396,647	350,550
Cost of revenue:
Product	59,037	51,219	45,752
Service	35,524	33,294	28,256
Total cost of revenue	94,561	84,513	74,008
Gross profit	359,108	312,134	276,542
Operating expenses:
Research and development	75,242	70,454	61,546
Sales and marketing	136,446	129,611	116,807
General and administrative	47,296	30,623	29,718
Amortization of acquired intangible assets	3,351	3,432	2,877
Restructuring charges	0	0	1,065
Total operating expenses	262,335	234,120	212,013
Income from operations	96,773	78,014	64,529
Interest and other expense, net:
Interest income	445	309	508
Interest expense	(773)	(768)	(1,291)
Other (expense) income, net	(1,480)	301	(10)
Total interest and other expense, net	(1,808)	(158)	(793)
Income before income tax expense	94,965	77,856	63,736
Income tax expense	33,773	28,750	23,127
Net income	$ 61,192	$ 49,106	$ 40,609
Basic net income per share (in dollars per share)	$ 1.49	$ 1.19	$ 0.97
Diluted net income per share (in dollars per share)	$ 1.47	$ 1.17	$ 0.96
Weighted average common shares outstanding used in computing:
Net income per share-basic (in shares)	41,105	41,366	41,665
Net income per share-diluted (in shares)	41,637	41,955	42,322