Tax Effects of Temporary Differences That Give Rise to Significant Portions of Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Apr. 30, 2015	Apr. 30, 2014
Deferred tax assets:
Accruals and expenses not deducted for tax purposes	$ 914	$ 1,024
State net operating loss carryforwards	350	389
Intangible assets and fixed asset basis differences	1,803	1,347
Nonqualified stock options	1,452	1,154
Total gross deferred tax assets	4,519	3,914
Less valuation allowance	461	466
Net deferred tax assets	4,058	3,448
Deferred tax liabilities:
Capitalized computer software development costs	(3,758)	(4,109)
Net gains/losses on trading securities	(605)	(566)
Goodwill	(752)	(598)
Other	(575)	(529)
Total gross deferred tax liabilities	(5,690)	(5,802)
Net deferred tax liabilities	$ (1,631)	$ (2,354)