Note I - Stock-based Compensation - Options Exercised (Details) - USD ($) $ in Thousands	3 Months Ended
Jul. 31, 2019	Jul. 31, 2018
Options exercised (in shares)	21,500	162,250
Cash received from option exercises	$ 80	$ 3,259
Intrinsic value of options exercised	$ 1,284	$ 5,508

Amount of cash inflow from exercise of option under share-based payment arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=SL79508275-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

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