Income Taxes - Income Tax Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Current tax expense (benefit):
Federal	$ 941	$ 247	$ 300
State and local	184	63	124
Foreign	791	838	185
Total current tax expense	1,916	1,148	609
Deferred tax expense (benefit):
Federal	(346)	(338)	170
State and local	(24)	(12)	83
Foreign	(6)	(59)	2
Total deferred tax expense (benefit)	(376)	(409)	255
Net income tax expense	$ 1,540	$ 739	$ 864