Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - $ / shares	Jan. 31, 2019	Apr. 30, 2018
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)	13,330,150	13,147,143
Common stock, shares outstanding (in shares)	6,685,013	6,849,161
Treasury stock, shares (in shares)	6,645,137	6,297,982