Note 2 - Supplementary Cash Flow Information - Supplementary Cash Flow Elements (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Cash and cash equivalents	$ 4,390	$ 7,590	$ 29,703
Restricted cash	305	305	305
Total cash, cash equivalents, and restricted cash shown in the Consolidated Statement of Cash Flows	4,695	7,895	30,008	$ 19,640
State and local income tax payments	1,090	923	894
Federal income tax payments	$ 5,448	$ 4,425	$ 5,400

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