Note K - Stock-based Compensation Plans (Tables)

12 Months Ended

Apr. 30, 2019

Notes Tables

Stock Option Plan Comparison [Table Text Block]

	Option Plan
Minimum exercise price as a percentage of fair market value at date of grant	100%
Last expiration date for outstanding options	May 8, 2028
Shares available for grant at April 30, 2019	298,500

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

	April 30, 2019	April 30, 2018	April 30, 2017
Expected terms (years)	5.5	5.5	5.5
Risk-free interest rate	2.79%	1.81%	1.47%
Volatility	36%	36%	36%
Dividend yield	-	-	-

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Options			Exercise Price per Share			Proceeds on Exercise			Weighted Average Exercise Price per Share
							(in thousands)
Outstanding at April 30, 2016		1,278,250					$	39,081		$	30.57
Granted		45,000		$26.42	to	$34.09		1,301			28.90
Exercised		(264,500	)	$11.90	to	$28.13		(4,739	)		17.92
Cancelled		(30,250	)	$41.86	to	$53.02		(1,559	)		51.55
Outstanding at April 30, 2017		1,028,500					$	34,084		$	33.51
Granted		25,000			$37.30			933			37.30
Exercised		(323,000	)	$11.90	to	$37.94		(6,692	)		20.72
Expired		(15,000	)	$44.52	to	$51.81		(710	)		47.26
Cancelled		(20,000	)	$41.86	to	$53.02		(932	)		46.61
Outstanding at April 30, 2018		695,500					$	26,683		$	30.50
Granted		145,000		$53.30	to	$54.85		7,915			54.58
Exercised		(275,000	)	$18.86	to	$53.30		(8,511	)		30.95
Outstanding at April 30, 2019		565,500					$	26,087		$	46.13

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

	Years Ended April 30,
(Dollars in thousands)	2019		2018		2017
Options Exercised		275,000		323,000		264,500
Cash Received from Options Exercised	$	5,663	$	2,832	$	2,609
Intrinsic Value of Options Exercised	$	10,817	$	8,381	$	6,439

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

	Number of Shares			Weighted Average Grant Date Fair Value
Unvested shares at April 30, 2016		9,500		$	52.10
Shares granted		10,000			39.14
Shares vested		-			-
Shares cancelled		(2,500	)		49.51
Unvested shares at April 30, 2017		17,000		$	44.86
Shares granted		166,500			45.86
Shares vested		-			-
Shares cancelled		(4,500	)		38.28
Unvested shares at April 30, 2018		179,000		$	45.96
Shares granted		3,000			53.30
Shares vested		-			-
Shares cancelled		(1,500	)		36.38
Unvested shares at April 30, 2019		180,500		$	46.16