Condensed Consolidated Statements of Equity (Unaudited) - 9 months ended Jan. 31, 2019 - 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	$ 361,988	$ (204,325)	$ 100	$ 230,535
Issuance of common stock (in shares)	1,124
Issuance of common stock		103				103
Stock options exercised (in shares)	181,883
Stock options exercised	$ 2	3,825				3,827
Purchase of 347,155 treasury shares				(24,087)		(24,087)
Stock based compensation		2,270				2,270
Dividends on subsidiary preferred stock			(30)			(30)
Net income			33,059			33,059
Balance (in shares) at Jan. 31, 2019	13,330,150
Balance at Jan. 31, 2019	$ 133	$ 78,839	$ 395,017	$ (228,412)	$ 100	$ 245,677