Furniture, Equipment and Purchased Software (Detail) - USD ($) $ in Thousands	Apr. 30, 2016	Apr. 30, 2015
Property, Plant and Equipment [Line Items]
Gross property plant and equipment	$ 35,833	$ 35,180
Accumulated depreciation and amortization	(32,437)	(31,632)
Net property plant and equipment	3,396	3,548
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Gross property plant and equipment	20,975	20,716
Computer equipment and purchased software
Property, Plant and Equipment [Line Items]
Gross property plant and equipment	10,303	10,049
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Gross property plant and equipment	$ 4,555	$ 4,415