Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - $ / shares	Oct. 31, 2017	Apr. 30, 2017
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	13,005,928	12,927,413
Common stock, shares outstanding (in shares)	7,177,213	7,608,471
Treasury stock, shares (in shares)	5,828,715	5,318,942