Note 4 - Supplementary Cash Flows Information - Supplementary Cash Flow Elements (Details) - USD ($) $ in Thousands	9 Months Ended
Jan. 31, 2024	Jan. 31, 2023	Apr. 30, 2023	Apr. 30, 2022
Cash and cash equivalents	$ 5,780	$ 11,861	$ 7,590
Restricted cash	305	305
Total cash, cash equivalents, and restricted cash shown in the Consolidated Condensed Statement of Cash Flows	6,085	12,166	$ 7,895	$ 30,008
State and local income tax payments	656	732
Federal income tax payments	$ 4,000	$ 3,327

Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including, but not limited to, disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482913/230-10-50-8

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 24
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-24

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-4

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant