Consolidated Statement of Equity (USD $) In Thousands, except Share data	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]	Total
Balance at April 30 at Apr. 30, 2011	$ 123	$ 46,476	$ 178,187	$ (37,875)	$ 100	$ 187,011
Balance at April 30 (in Shares) at Apr. 30, 2011	12,276,658
Issuance of common stock		118				118
Issuance of common stock (in Shares)	3,862
Stock options exercised	1	1,370				1,371
Stock options exercised (in Shares)	88,647					88,647
Purchase of treasury shares				(39,367)		(39,367)
Tax benefit of restricted stock vested		221				221
Stock based compensation		2,172				2,172
Stock based compensation (in Shares)	2,000
Dividends on subsidiary preferred stock			(40)			(40)
Net income			32,987			32,987
Balance at April 30 at Apr. 30, 2012	124	50,357	211,134	(77,242)	100	184,473
Balance at April 30 (in Shares) at Apr. 30, 2012	12,371,167
Issuance of common stock		143				143
Issuance of common stock (in Shares)	4,242
Stock options exercised		790				790
Stock options exercised (in Shares)	35,750					35,750
Purchase of treasury shares				(17,305)		(17,305)
Tax benefit of restricted stock vested		190				190
Stock based compensation		1,852				1,852
Stock based compensation (in Shares)	3,500
Dividends on subsidiary preferred stock			(40)			(40)
Net income			32,165			32,165
Balance at April 30 at Apr. 30, 2013	124	53,332	243,259	(94,547)	100	202,268
Balance at April 30 (in Shares) at Apr. 30, 2013	12,414,659
Issuance of common stock		151				151
Issuance of common stock (in Shares)	4,150
Stock options exercised	1	719				720
Stock options exercised (in Shares)	30,500					30,500
Purchase of treasury shares				(12,754)		(12,754)
Tax benefit of restricted stock vested		141				141
Stock based compensation		1,391				1,391
Stock based compensation (in Shares)	3,500
Dividends on subsidiary preferred stock			(40)			(40)
Net income			21,129			21,129
Balance at April 30 at Apr. 30, 2014	$ 125	$ 55,734	$ 264,348	$ (107,301)	$ 100	$ 213,006
Balance at April 30 (in Shares) at Apr. 30, 2014	12,452,809