Summary of Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Apr. 30, 2013
Accrued Expenses [Line Items]
Accrued employee benefits	$ 2,456	$ 1,953
Accrued professional fees	2,338	2,882
Accrued rebates and promotions	1,327	3,900
Accrued workers' compensation	890	963
Interest payable	762	1,542
Accrued commissions	595	949
Accrued utilities	528	537
Current portion of capital lease obligation	462	442
Accrued distributor incentives	153	458
Accrued other	1,318	2,407
Total accrued expenses	$ 10,829	$ 16,033