Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - 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 deficit	Treasury stock
Beginning balance (in shares) at Apr. 30, 2022					36,405,695		1,821,587
Beginning balance at Apr. 30, 2022		$ 132,041			$ 3,641		$ 182	$ 171,948	$ (18,171)	$ (25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)		97,800			97,800	[1]
Proceeds from stock options exercised	[1]	$ 1,145			$ 9			1,136
Stock-based compensation		2,649						2,649
Net earnings		4,169							4,169
Dividends declared*	[1]	(7,416)							(7,416)
Ending balance (in shares) at Oct. 31, 2022					36,503,495		1,821,587
Ending balance at Oct. 31, 2022		132,588			$ 3,650		$ 182	175,733	(21,418)	(25,559)
Beginning balance (in shares) at Jul. 31, 2022					36,448,695		1,821,587
Beginning balance at Jul. 31, 2022		132,177			$ 3,645		$ 182	173,721	(19,812)	(25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)					54,800
Proceeds from stock options exercised		674			$ 5			669
Stock-based compensation		1,343						1,343
Net earnings		2,105							2,105
Dividends declared*	[1]	(3,711)							(3,711)
Ending balance (in shares) at Oct. 31, 2022					36,503,495		1,821,587
Ending balance at Oct. 31, 2022		132,588			$ 3,650		$ 182	175,733	(21,418)	(25,559)
Beginning balance (in shares) at Apr. 30, 2023			36,907,242	1,821,587	36,907,242		1,821,587
Beginning balance at Apr. 30, 2023		$ 138,288			$ 3,691		$ 182	182,722	(22,748)	(25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)		22,253			22,253	[1]
Proceeds from stock options exercised	[1]	$ 246			$ 2			244
Stock-based compensation		3,134						3,134
Purchases of common stock		(4,814)	$ (30,400)							(4,814)
Net earnings		5,111							5,111
Dividends declared*	[1]	(7,515)							(7,515)
Ending balance (in shares) at Oct. 31, 2023			36,929,495	1,821,587	36,929,495		1,821,587
Ending balance at Oct. 31, 2023		134,450			$ 3,693		$ 182	186,100	(25,152)	(30,373)
Beginning balance (in shares) at Jul. 31, 2023					36,929,495		1,821,587
Beginning balance at Jul. 31, 2023		139,079			$ 3,693		$ 182	184,520	(23,757)	(25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		1,580						1,580
Purchases of common stock		(4,814)								(4,814)
Net earnings		2,363							2,363
Dividends declared*		(3,758)							(3,758)
Ending balance (in shares) at Oct. 31, 2023			36,929,495	1,821,587	36,929,495		1,821,587
Ending balance at Oct. 31, 2023		$ 134,450			$ 3,693		$ 182	$ 186,100	$ (25,152)	$ (30,373)

[1] Amounts adjusted for rounding