Note 8 - Federal, State and Local Income Taxes - Effective Income Tax Rate Reconciliation (Details)	6 Months Ended
Oct. 31, 2019	Oct. 31, 2018
U.S. statutory federal tax rate	21.00%	21.00%
State and local income taxes, net of federal income tax benefit	6.45%	(1.62%)
Effect of dividends received deductions	(0.20%)	(0.24%)
Other, net	0.04%	0.00%
Effective income tax rate	27.29%	19.14%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deduction for dividend.

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