Summary of Significant Accounting Policies - Schedule of Property Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified							12 Months Ended				12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014 Land [Member]	Apr. 30, 2013 Land [Member]	Apr. 30, 2014 Building and improvements [Member]	Apr. 30, 2013 Building and improvements [Member]	Apr. 30, 2014 Building and improvements [Member] Minimum [Member]	Apr. 30, 2014 Building and improvements [Member] Maximum [Member]	Apr. 30, 2014 Machinery and equipment [Member]	Apr. 30, 2013 Machinery and equipment [Member]	Apr. 30, 2014 Machinery and equipment [Member] Minimum [Member]	Apr. 30, 2014 Machinery and equipment [Member] Maximum [Member]
Depreciation Amortization Impairment [Line Items]
Useful Life							10 years	40 years			5 years	10 years
Property plant and equipment gross	$ 46,391	$ 45,109	$ 41	$ 41	$ 15,221	$ 14,921			$ 31,129	$ 30,147
Less accumulated depreciation	(31,821)	(30,011)
Net property, plant and equipment	$ 14,570	$ 15,098