Note H - Income Taxes (Details) - Reconciliation of Income Tax to Statutory Rate (USD $) In Thousands, unless otherwise specified	12 Months Ended
Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Reconciliation of Income Tax to Statutory Rate [Abstract]
Tax provision at statutory rate	$ 16,463	$ 11,785	$ 17,729
State taxes, net of federal benefit	1,172	813	829
Other, net	(91)	(55)	(67)
	$ 17,544us-gaap_IncomeTaxExpenseBenefit	$ 12,543us-gaap_IncomeTaxExpenseBenefit	$ 18,491us-gaap_IncomeTaxExpenseBenefit

Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority noncontrolling interest income (loss), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, increase (decrease) in enacted tax rate, prior year income taxes, increase (decrease) in deferred tax asset valuation allowance, and other adjustments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration