Note I - Stock-based Compensation - Options Exercised (Details) - USD ($) $ in Thousands	6 Months Ended
Oct. 31, 2021	Oct. 31, 2020
Options exercised (in shares)	56,500	55,566
Cash received from option exercises	$ 251	$ 2,548
Intrinsic value of options exercised	$ 4,896	$ 2,439

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=120381028&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=123570139&loc=d3e3255-108585

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