Summary of Significant Accounting Policies - Schedule of Activity in Allowance for Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
Accounting Policies [Abstract]
Balance at beginning of year	$ 194	$ 311	$ 250
Bad debt provision	116	34	214
Doubtful accounts written off (net)	(81)	(151)	(153)
Balance at end of year	$ 229	$ 194	$ 311