Note 8 - Federal, State and Local Income Taxes - Effective Income Tax Rate Reconciliation (Details) (Parentheticals)	9 Months Ended	12 Months Ended
Jan. 31, 2019	Jan. 31, 2018	Apr. 30, 2017
U.S. statutory federal tax rate	21.00%	30.33%	35.00%

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

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