Additional number of common shares reserved for future issuance.

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Unrecognized cost of not currently expected to vest share-based compensation awards.

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No definition available.

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Represents the number of options exercised through net settlements during the period in accordance with plan provisions.

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No definition available.

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Represents the number of options exercised through net settlements during the period in accordance with plan provisions, net of shares to satisfy the exercise price and applicable withholding taxes.

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No definition available.

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The grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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With regard to stock options, this element represents the reduction in shares issued during the period to satisfy the exercise price and applicable withholding taxes.

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No definition available.

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As of the balance sheet date, the number of shares into which not currently expected to vest stock options outstanding can be converted under the option plan.

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No definition available.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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-Paragraph 1
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The amount of expense, net of income tax, recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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No definition available.

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Aggregate number of common shares reserved for future issuance.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Gross number of share options (or share units) granted during the period.

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No definition available.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Note K - Stock-based Compensation Plans (Details Textual) - USD ($)		12 Months Ended
	Aug. 05, 2015	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016	Oct. 14, 2009	Oct. 13, 2009
Allocated Share-based Compensation Expense, Total		$ 1,600,000	$ 1,300,000	$ 1,500,000
Allocated Share-based Compensation Expense, Net of Tax		$ 1,100,000	$ 811,000	$ 952,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		25,000	45,000	338,750
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value		$ 10,400,000	$ 8,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Options Exercised Through Net Settlements		187,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Reduction in Shares Issued to Satisfy the Exercise Price and Applicable Withholding Taxes		106,366
Share-based Compensation Arrangement by Share-based Payment Award, Options Exercised Through Net Settlements, Net of Shares to Satisfy the Exercise Price and Applicable Withholding Taxes		80,634
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number		367,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value		$ 8,400,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term		2 years 240 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price		$ 30.50
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		5 years
Employee Stock Option [Member]
Allocated Share-based Compensation Expense, Total		$ 1,200,000	1,200,000	$ 1,400,000
Allocated Share-based Compensation Expense, Net of Tax		773,000	728,000	870,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total		$ 1,700,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		1 year 328 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		25,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Fair Value		$ 336,000	461,000	5,600,000
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		5 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		126,500
Employee Service Share-based Compensation, Not Currently Expected to Vest Awards, Compensation Cost Not yet Recognized		$ 1,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Not Currently Expected to Vest, Outstanding, Number		61,000
Restated Option Plan [Member]
Common Stock, Additional Capital Shares Reserved for Future Issuance	300,000
Common Stock, Capital Shares Reserved for Future Issuance	1,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		297,500
Restated Option Plan [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Stock Incentive Plan [Member]
Allocated Share-based Compensation Expense, Total		$ 430,000	107,000	99,000
Allocated Share-based Compensation Expense, Net of Tax		288,000	67,000	62,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total		$ 7,600,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		8 years 73 days
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized					300,000	150,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value		$ 8,200,000	$ 763,000	$ 495,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		166,500	10,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 45.86	$ 39.14
Stock Incentive Plan [Member] \| First Issuance of Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		132,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 48.70
Stock Incentive Plan [Member] \| Second Issuance of Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		34,500
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 35
Stock Incentive Plan [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			10,000	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 39.14
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		8,027