Condensed Consolidated Statements of Equity (Unaudited) - 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, 2018	13,147,143
Balance at Apr. 30, 2018	$ 131	$ 72,641	$ 361,987	$ (204,325)	$ 100	$ 230,534
Issuance of common stock (in shares)	544,000
Issuance of common stock		29				29
Stock options exercised (in shares)	131,357
Stock options exercised	$ 2	2,711				2,713
Purchase of treasury shares				(7,377)		(7,377)
Stock based compensation		1,094				1,094
Dividends on subsidiary preferred stock			(10)			(10)
Net income			10,884			10,884
Balance (in shares) at Jul. 31, 2018	13,279,044
Balance at Jul. 31, 2018	$ 133	76,475	372,861	(211,702)	100	237,867
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)	552,000
Issuance of common stock		40				40
Stock options exercised (in shares)	15,815
Stock options exercised		80				80
Purchase of treasury shares				(4,715)		(4,715)
Stock based compensation		1,620				1,620
Dividends on subsidiary preferred stock			(10)			(10)
Net income			15,511			15,511
Balance (in shares) at Jul. 31, 2019	13,392,397
Balance at Jul. 31, 2019	$ 134	$ 83,345	$ 425,074	$ (235,617)	$ 100	$ 273,036