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)		399,000			399,000
Proceeds from stock options exercised		$ 4,072			$ 40			4,032
Stock-based compensation		775						775
Net earnings		2,947							2,947
Dividends declared	[1]	(3,651)							(3,651)
Ending balance (in shares) at Jul. 31, 2021					36,028,566		1,821,587
Ending balance at Jul. 31, 2021		126,534			$ 3,603		$ 182	164,299	(15,991)	(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)		43,000			43,000	[1]
Proceeds from stock options exercised	[1]	$ 471			$ 4			467
Stock-based compensation		1,306						1,306
Net earnings		2,133							2,133
Dividends declared		(3,705)							(3,705)
Ending balance (in shares) at Jul. 31, 2022			36,448,695	1,821,587	36,448,695		1,821,587
Ending balance at Jul. 31, 2022		$ 133,181			$ 3,645		$ 182	$ 173,721	$ (18,808)	$ (25,559)

[1] Amounts adjusted for rounding