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, 2021					35,629,566	1,821,587
Beginning 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)		545,242			545,242
Proceeds from stock options exercised		$ 5,714			$ 54		5,660
Stock-based compensation		1,817					1,817
Net earnings		6,261						6,261
Dividends declared	[1]	(7,336)						(7,336)
Ending balance (in shares) at Oct. 31, 2021					36,174,808	1,821,587
Ending balance at Oct. 31, 2021		128,847			$ 3,617	$ 182	166,969	(16,362)	(25,559)
Beginning balance (in shares) at Jul. 31, 2021					36,028,566	1,821,587
Beginning balance at Jul. 31, 2021		126,534			$ 3,603	$ 182	164,299	(15,991)	(25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)					146,242
Proceeds from stock options exercised		1,642			$ 14		1,628
Stock-based compensation		1,042					1,042
Net earnings		3,314						3,314
Dividends declared	[2]	(3,685)						(3,685)
Ending balance (in shares) at Oct. 31, 2021					36,174,808	1,821,587
Ending balance at Oct. 31, 2021		128,847			$ 3,617	$ 182	166,969	(16,362)	(25,559)
Beginning balance (in shares) at Apr. 30, 2022			36,405,695	1,821,587	36,405,695	1,821,587
Beginning balance at Apr. 30, 2022		$ 132,976			$ 3,641	$ 182	171,948	(17,236)	(25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)		97,800			97,800
Proceeds from stock options exercised		$ 1,145			$ 9		1,136
Stock-based compensation		2,649					2,649
Net earnings		4,214						4,214
Dividends declared	[1]	(7,416)						(7,416)
Ending balance (in shares) at Oct. 31, 2022			36,503,495	1,821,587	36,503,495	1,821,587
Ending balance at Oct. 31, 2022		133,568			$ 3,650	$ 182	175,733	(20,438)	(25,559)
Beginning balance (in shares) at Jul. 31, 2022					36,448,695	1,821,587
Beginning balance at Jul. 31, 2022		133,181			$ 3,645	$ 182	173,721	(18,808)	(25,559)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from stock options exercised (in shares)	[2]				54,800
Proceeds from stock options exercised	[2]	674			$ 5		669
Stock-based compensation		1,343					1,343
Net earnings		2,081						2,081
Dividends declared		(3,711)						(3,711)
Ending balance (in shares) at Oct. 31, 2022			36,503,495	1,821,587	36,503,495	1,821,587
Ending balance at Oct. 31, 2022		$ 133,568			$ 3,650	$ 182	$ 175,733	$ (20,438)	$ (25,559)

[1] Amounts adjusted for rounding

[2] Amounts adjusted for rounding