Note K - Stock-Based Compensation Plans (Tables)

12 Months Ended

Apr. 30, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Option Plan Comparison [Table Text Block]

	1997 Plan	2007 Plan
Minimum exercise price as a percentage of fair market value at date of grant	100%	100%
Last expiration date for outstanding options	July 2, 2017	November 20, 2024
Shares available for grant at April 30, 2015	-	290,500

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	April 30, 2015	April 30, 2014	April 30, 2013
Expected terms (years)	5.4	5.0	5.0
Risk-free interest rate	1.64%	0.67%	0.78%
Volatility	34%	50%	50%
Dividend yield	-	-	-

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

	Number of Shares			Exercise Price per Share			Proceeds on Exercise			Weighted Average Exercise Price per Share
							(in thousands)
Outstanding at April 30, 2012		1,118,250		$11.83	to	$45.72	$	22,881		$	20.46
Granted		40,000		$44.14	to	$45.46		1,801			45.02
Exercised		(35,750	)	$11.83	to	$23.34		(790	)		22.13
Outstanding at April 30, 2013		1,122,500		$11.90	to	$45.72	$	23,892		$	21.28
Granted		25,000		$44.52	to	$46.44		1,122			44.90
Exercised		(30,500	)	$23.34	to	$23.75		(720	)		23.58
Outstanding at April 30, 2014		1,117,000		$11.90	to	$46.44	$	24,294		$	21.75
Granted		89,000		$36.54	to	$50.25		3,997			44.91
Exercised		(212,250	)	$11.90	to	$45.46		(4,143	)		19.52
Cancelled		(12,000	)	$41.86	to	$45.72		(540	)		45.08
Outstanding at April 30, 2015		981,750		$11.90	to	$50.25	$	23,608		$	24.05

Schedule of Share-based Compensation, Stock Options, Exercises [Table Text Block]

	Twelve Months Ended April 30,
(Dollars in thousands)	2015			2014			2013
Options Exercised			212,250			30,500			35,750
Cash Received from Options Exercised		$	4,143		$	720		$	790
Intrinsic Value of Options Exercised		$	5,983		$	563		$	811

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Number of Shares			Weighted Average Grant Date Fair Value
Unvested shares at April 30, 2014		20,000		$	24.47
Shares granted		9,500			52.10
Shares vested		(20,000	)		24.47
Unvested shares at April 30, 2015		9,500		$	52.10