Consolidated Condensed Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Jan. 31, 2013	Apr. 30, 2012
Statement Of Financial Position [Abstract]
Short term investments (in dollars)	$ 7,751	$ 10,848
Allowance for doubtful accounts (in dollars)	$ 35	$ 44
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized	30,000,000	30,000,000
Common stock, shares issued	10,000,000	10,000,000
Treasury stock, shares	119,949	103,619	[1],[2]

[1] Includes the balance of 18,400 shares with a total average cost of $354,000 that were acquired prior to the repurchase program authorized in January 2011.

[2] Includes the balance of 85,219 shares with a total average cost of $1,036,000 that were acquired during the former repurchase program, which was authorized in January 2011 and expired in January 2012.