Quarterly Financial Information (Unaudited) - Quarterly Operating Results (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2015		Apr. 30, 2014		Apr. 30, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 48,317	$ 49,562	$ 47,325	$ 45,977	$ 43,078	$ 43,600	$ 41,148	$ 40,319	$ 191,181		$ 168,145		$ 146,812
Cost of revenue	18,148	17,988	17,414	16,356	14,522	13,758	12,508	12,117	69,906	[1]	52,905	[1]	47,350	[1]
Gross profit	30,169	31,574	29,911	29,621	28,556	29,842	28,640	28,202	121,275		115,240		99,462
Operating expenses:
Sales and marketing	20,427	18,020	18,931	20,995	23,884	20,765	20,837	20,996	78,373	[1]	86,482	[1]	73,114	[1]
Research and development	9,880	8,779	9,306	9,730	9,832	9,036	9,793	8,924	37,695	[1]	37,585	[1]	32,169	[1]
General and administrative	7,582	6,932	8,100	7,893	6,521	7,674	3,639	8,536	30,507	[1]	26,370	[1]	30,990	[1]
Acquisition-related and other	815	413	2,326	492	366	31	8,283	7,504	4,046		16,184		10,487
Amortization of acquired intangible assets	309	309	310	309	288	282	283	282	1,237		1,135		549
Total operating expenses	39,013	34,453	38,973	39,419	40,891	37,788	42,835	46,242	151,858		167,756		147,309
Operating loss	(8,844)	(2,879)	(9,062)	(9,798)	(12,335)	(7,946)	(14,195)	(18,040)	(30,583)		(52,516)		(47,847)
Total other income (expense), net	(521)	(920)	(588)	(498)	(316)	(268)	(249)	3	(2,527)		(830)		(828)
Net loss before income taxes	(9,365)	(3,799)	(9,650)	(10,296)	(12,651)	(8,214)	(14,444)	(18,037)	(33,110)		(53,346)		(48,675)
Income tax expense (benefit)	(540)	324	258	12	(418)	179	130	(391)	54		(500)		(1,172)
Net loss from continuing operations	(8,825)	(4,123)	(9,908)	(10,308)	(12,233)	(8,393)	(14,574)	(17,646)	(33,164)		(52,846)		(47,503)
Income (loss) from discontinued operations, net of tax				(1,257)	(11,448)	430	420	278	(1,257)		(10,320)		(16,249)
Net loss applicable to common stockholders	$ (8,825)	$ (4,123)	$ (9,908)	$ (11,565)	$ (23,681)	$ (7,963)	$ (14,154)	$ (17,368)	$ (34,421)		$ (63,166)		$ (63,752)
Basic earnings (loss) per share:
Continuing operations	$ (0.11)	$ (0.05)	$ (0.13)	$ (0.13)	$ (0.16)	$ (0.11)	$ (0.20)	$ (0.23)
Discontinued operations				(0.02)	(0.15)	0.01	0.01
Basic loss per share:	(0.11)	(0.05)	(0.13)	(0.15)	(0.31)	(0.10)	(0.19)	(0.23)
Diluted earnings per share:
Continuing operations	$ 0	$ 0	$ 0	$ 0	$ 0	0	0	$ 0
Discontinued operations						0.01	0.01
Diluted earnings per share:						$ 0.01	$ 0.01

[1] Includes stock-based expense as follows: Cost of revenue $ 1,517 $ 1,155 $ 677 Sales and marketing 3,923 4,496 3,033 Research and development 2,561 2,817 2,840 General and administrative 4,677 5,357 4,608