Consolidated Statements of Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Apr. 30, 2019	13,376,030
Balance at Apr. 30, 2019	$ 134	$ 81,605	$ 409,573	$ (230,902)	$ 100	$ 260,510
Issuance of common stock (in shares)	9,760
Issuance of common stock		190				$ 190
Stock options exercised (in shares)	92,943					121,250
Stock options exercised	$ 1	1,532				$ 1,533
Purchase of treasury shares				(16,009)		(16,009)
Stock based compensation		4,732				4,732
Issuance of restricted stock		500				500
Dividends on subsidiary preferred stock			(40)			(40)
Net income			51,343			51,343
Balance (in shares) at Apr. 30, 2020	13,478,733
Balance at Apr. 30, 2020	$ 135	88,559	460,876	(246,911)	100	302,759
Issuance of common stock (in shares)	2,921
Issuance of common stock		258				$ 258
Stock options exercised (in shares)	110,235					131,350
Stock options exercised	$ 1	4,033				$ 4,034
Purchase of treasury shares				(10,616)		(10,616)
Stock based compensation		5,962				5,962
Dividends on subsidiary preferred stock			(40)			(40)
Net income			104,139			104,139
Balance (in shares) at Apr. 30, 2021	13,591,889
Balance at Apr. 30, 2021	$ 136	98,812	564,975	(257,527)	100	406,496
Issuance of common stock (in shares)	9,721
Issuance of common stock		293				$ 293
Stock options exercised (in shares)	40,575					94,000
Stock options exercised		(1,488)				$ (1,488)
Purchase of treasury shares				(34,698)		(34,698)
Stock based compensation		5,496				5,496
Dividends on subsidiary preferred stock			(40)			(40)
Net income			93,307			93,307
Balance (in shares) at Apr. 30, 2022	13,642,185
Balance at Apr. 30, 2022	$ 136	$ 103,113	$ 658,242	$ (292,225)	$ 100	$ 469,366