CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Statement Of Financial Position [Abstract]
Allowance for receivables	$ 194	$ 311
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	5,000	5,000
Common stock, shares issued	2,620	2,620
Common stock, shares outstanding	2,592	2,579
Treasury stock, shares	27	40