Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Trade accounts receivable, allowance for doubtful accounts	$ 264	$ 153
Class A Common Shares
Common stock, par value (in usd per share)	$ 0.10	$ 0.10
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	35,000,649	33,979,739
Common stock, shares issued, net	30,412,017	29,391,107
Common stock, shares Outstanding	35,000,649	33,979,739
Common stock, shares Outstanding, net	30,412,017	29,391,107
Class A treasury stock shares	4,588,632	4,588,632
Class B Common Shares
Common stock, par value (in usd per share)	$ 0.10	$ 0.10
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	1,821,587	1,821,587
Common stock, shares Outstanding	1,821,587	1,821,587