Significant Components of Deferred Income Tax (Benefit) Expense Attributable to Income from Continuing Operations before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Significant Components Of Deferred Income Tax Expense [Line Items]
Deferred tax (benefit)/expense	$ (728)	$ 582	$ 351
(Decrease) increase in the valuation allowance for deferred tax assets	(5)	45	(187)
Deferred Income Tax Expense (Benefit), Net of Valuation Allowance, Total	$ (733)	$ 627	$ 164