Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Apr. 30, 2015	Apr. 30, 2014
Allowance for doubtful accounts receivable	$ 215	$ 222
Class A treasury stock, shares	4,568,297	4,444,815
Class A Common Shares
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	30,566,099	30,075,187
Class B Common Shares
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	2,587,086	2,587,086
Common stock, shares outstanding	2,587,086	2,587,086