Quarterly Operating Results (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2014		Apr. 30, 2013		Apr. 30, 2012
Quarterly Financial Information [Line Items]
Revenue	$ 43,078	$ 43,600	$ 41,148	$ 40,319	$ 38,924	$ 38,920	$ 35,148	$ 33,820	$ 168,145		$ 146,812		$ 106,136
Cost of revenue	14,522	13,758	12,508	12,117	12,319	12,130	11,672	11,229	52,905	[1]	47,350	[1]	37,416	[1]
Gross profit	28,556	29,842	28,640	28,202	26,605	26,790	23,476	22,591	115,240		99,462		68,720
Operating expenses:
Sales and marketing	23,884	20,765	20,837	20,996	22,095	20,103	17,165	13,751	86,482	[1]	73,114	[1]	49,273	[1]
Research and development	9,832	9,036	9,793	8,924	8,691	8,822	7,496	7,160	37,585	[1]	32,169	[1]	21,266	[1]
General and administrative	6,521	7,674	3,639	8,536	9,672	8,125	6,533	6,660	26,370	[1]	30,990	[1]	20,896	[1]
Acquisition-related and other	366	31	8,283	7,504	7,819	1,583	1,085		16,184		10,487
Amortization of acquired intangible assets	288	282	283	282	282	267			1,135		549
Total operating expenses	40,891	37,788	42,835	46,242	48,559	38,900	32,279	27,571	167,756		147,309		91,435
Operating loss	(12,335)	(7,946)	(14,195)	(18,040)	(21,954)	(12,110)	(8,803)	(4,980)	(52,516)		(47,847)		(22,715)
Total other income (expense), net	(316)	(268)	(249)	3	(483)	8	54	(407)	(830)		(828)		(803)
Net loss before income taxes	(12,651)	(8,214)	(14,444)	(18,037)	(22,437)	(12,102)	(8,749)	(5,387)	(53,346)		(48,675)		(23,518)
Income tax expense (benefit)	(418)	179	130	(391)	583	(2,295)	271	269	(500)		(1,172)		811
Net loss from continuing operations	(12,233)	(8,393)	(14,574)	(17,646)	(23,020)	(9,807)	(9,020)	(5,656)	(52,846)		(47,503)		(24,329)
Income (loss) from discontinued operations, net of tax	(11,448)	430	420	278	(124)	(1,020)	(2,222)	(12,883)	(10,320)		(16,249)
Net loss applicable to common stockholders	$ (23,681)	$ (7,963)	$ (14,154)	$ (17,368)	$ (23,144)	$ (10,827)	$ (11,242)	$ (18,539)	$ (63,166)		$ (63,752)		$ (24,329)
Basic earnings (loss) per share:
Continuing operations	$ (0.16)	$ (0.11)	$ (0.20)	$ (0.23)	$ (0.32)	$ (0.14)	$ (0.13)	$ (0.09)
Discontinued operations	$ (0.15)	$ 0.01	$ 0.01			$ (0.01)	$ (0.03)	$ (0.21)
Basic loss per share:	$ (0.31)	$ (0.10)	$ (0.19)	$ (0.23)	$ (0.32)	$ (0.15)	$ (0.16)	$ (0.30)
Diluted earnings per share:
Continuing operations
Discontinued operations		$ 0.01	$ 0.01
Diluted earnings per share:		$ 0.01	$ 0.01

[1] Includes stock-based expense as follows: Cost of revenue $ 1,155 $ 677 $ 1,239 Sales and marketing 4,496 3,033 1,881 Research and development 2,817 2,840 1,335 General and administrative 5,357 4,608 3,255