Income Taxes (Narrative) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Components Of Income Tax Expense Benefit [Line Items]
Benefit for income taxes	$ (4,963)	$ 601	$ (3,899)	$ 1,330
Provisions for income taxes deferred			(4,057)	1,548
Provision for income taxes current			167	245
BBI Acquisition [Member]
Components Of Income Tax Expense Benefit [Line Items]
Deferred tax liability recorded through goodwill	5,242		5,242
Deferred tax benefit due to reduction in valuation allowance	5,242		5,242
Provisions for income taxes deferred			$ 1,193	$ 1,085