Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands		Total	Class A Common Shares	Class B Common Shares	Common stock Class A Common Shares		Common stock Class B Common Shares	Additional paid-in capital	Retained earnings/deficit	Treasury stock
Beginning Balance (in shares) at Apr. 30, 2019					33,979,739		1,821,587
Beginning Balance at Apr. 30, 2019		$ 114,607			$ 3,398		$ 182	$ 138,315	$ (1,729)	$ (25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)		1,020,910			1,020,910
Proceeds from stock options exercised		$ 10,072			$ 102			9,970
Stock-based compensation		2,027						2,027
Net earnings		6,742							6,742
Dividends declared ($0.44 per share)		(14,026)							(14,026)
Ending Balance (in shares) at Apr. 30, 2020					35,000,649		1,821,587
Ending Balance at Apr. 30, 2020		$ 119,422			$ 3,500		$ 182	150,312	(9,013)	(25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)		628,917			628,917
Proceeds from stock options exercised		$ 6,697			$ 63			6,634
Stock-based compensation		2,546						2,546
Net earnings		8,089							8,089
Dividends declared ($0.44 per share)	[1]	(14,363)							(14,363)
Ending Balance (in shares) at Apr. 30, 2021			35,629,566	1,821,587	35,629,566		1,821,587
Ending Balance at Apr. 30, 2021		$ 122,391			$ 3,563		$ 182	159,492	(15,287)	(25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)		776,129			776,129	[1]
Proceeds from stock options exercised	[1]	$ 8,578			$ 78			8,500
Stock-based compensation		3,956						3,956
Net earnings		12,782							12,782
Dividends declared ($0.44 per share)	[1]	(14,731)							(14,731)
Ending Balance (in shares) at Apr. 30, 2022			36,405,695	1,821,587	36,405,695		1,821,587
Ending Balance at Apr. 30, 2022		$ 132,976			$ 3,641		$ 182	$ 171,948	$ (17,236)	$ (25,559)

[1] *Amounts adjusted for rounding