Components of Net Deferred Tax Amounts Recognized in Accompanying Consolidated Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Deferred tax assets:
Bad debts	$ 761	$ 268
Other accruals	2,158	598
Charitable contributions	216	119
Stock options	3,476	1,520
State tax credit	15	16
Net operating losses	45,309	15,412
Research and development credit	3,169	1,355
Deferred rent	1,045	1,099
Deferred revenue	1,694	1,824
Total deferred tax assets	57,843	22,211
Less valuation allowance	(37,902)	(19,854)
Net deferred tax assets	19,941	2,357
Deferred tax liability:
Intangible assets	(16,756)
Depreciation	(3,152)	(2,116)
Total deferred tax liability	(19,908)	(2,116)
Total net deferred tax assets	$ 33	$ 241