Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
Condensed Consolidated Statements of Operations [Abstract]
Revenue	$ 38,626	$ 25,015	$ 74,288	$ 47,103
Cost of revenue	14,099	8,805	26,732	16,602
Gross profit	24,527	16,210	47,556	30,501
Operating expenses:
Sales and marketing	17,850	12,125	33,172	23,317
Research and development	7,948	4,576	15,442	7,919
General and administrative	7,484	4,815	23,680	9,914
Acquisition-related and other	1,366		2,750
Amortization of acquired intangible assets	898		1,378
Total operating expenses	35,546	21,516	76,422	41,150
Operating loss	(11,019)	(5,306)	(28,866)	(10,649)
Other income (expense), net
Interest income		6	50	13
Other income (expense)	51	(373)	(403)	(464)
Total other income (expense), net	51	(367)	(353)	(451)
Loss before income taxes	(10,968)	(5,673)	(29,219)	(11,100)
Income tax expense	274	178	562	287
Net loss	(11,242)	(5,851)	(29,781)	(11,387)
Accretion of redeemable convertible preferred stock		(12)		(25)
Net loss applicable to common stockholders	$ (11,242)	$ (5,863)	$ (29,781)	$ (11,412)
Net loss per share applicable to common stockholders:
Basic and diluted	$ (0.16)	$ (0.30)	$ (0.45)	$ (0.60)
Basic and diluted weighted average number of shares outstanding	69,846	19,421	66,203	19,119