Condensed Statements of Stockholders' Equity (Unaudited) - USD ($)	Preferred Stock [Member]	Common Stock Class A [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Total
Beginning balance, value at Apr. 30, 2021	$ 99,000	$ 850,000	$ 1,934,000	$ (4,336,000)	$ 108,000	$ 49,749,000	$ 48,404,000
Beginning balance, shares at Apr. 30, 2021	4,100	8,502,881		3,556,412
Purchases of common stock				$ 26,000			26,000
Dividend declared at per common share outstanding						(2,472,000)	(2,472,000)
Unrealized gain (loss), net of tax effect					(36,000)		(36,000)
Net Income						3,434,000	3,434,000
Purchases of common stock, shares				2,013
Ending balance, value at Oct. 31, 2021	$ 99,000	$ 850,000	1,934,000	$ (4,362,000)	72,000	50,711,000	49,304,000
Ending balance, shares at Oct. 31, 2021	4,100	8,502,881		3,558,425
Beginning balance, value at Jul. 31, 2021	$ 99,000	$ 850,000	1,934,000	$ (4,336,000)	115,000	51,495,000	50,157,000
Beginning balance, shares at Jul. 31, 2021	4,100	8,502,881		3,556,425
Purchases of common stock				$ (26,000)			(26,000)
Dividend declared at per common share outstanding						(2,472,000)	(2,472,000)
Unrealized gain (loss), net of tax effect					(43,000)		(43,000)
Net Income						1,688,000	1,688,000
Purchases of common stock, shares				2,000
Ending balance, value at Oct. 31, 2021	$ 99,000	$ 850,000	1,934,000	$ (4,362,000)	72,000	50,711,000	49,304,000
Ending balance, shares at Oct. 31, 2021	4,100	8,502,881		3,558,425
Beginning balance, value at Apr. 30, 2022	$ 99,000	$ 850,000	1,934,000	$ (4,547,000)	(137,000)	50,843,000	49,042,000
Beginning balance, shares at Apr. 30, 2022	4,100	8,502,881		3,571,693
Purchases of common stock				$ (3,000)			(3,000)
Dividend declared at per common share outstanding						(2,959,000)	(2,959,000)
Unrealized gain (loss), net of tax effect					(126,000)		(126,000)
Net Income						1,659,000	1,659,000
Purchases of common stock, shares				270
Prior period adjustment for provisions related to depreciation						(161,000)	(161,000)
Ending balance, value at Oct. 31, 2022	$ 99,000	$ 850,000	1,934,000	$ (4,550,000)	(263,000)	49,382,000	47,452,000
Ending balance, shares at Oct. 31, 2022	4,100	8,502,881		3,571,963
Beginning balance, value at Jul. 31, 2022	$ 99,000	$ 850,000	1,934,000	$ (4,549,000)	(117,000)	51,733,000	49,950,000
Beginning balance, shares at Jul. 31, 2022	4,100	8,502,881		3,571,893
Purchases of common stock				$ (1,000)			(1,000)
Dividend declared at per common share outstanding						(2,958,000)	(2,958,000)
Unrealized gain (loss), net of tax effect					(146,000)		(146,000)
Net Income						607,000	607,000
Purchases of common stock, shares				70
Ending balance, value at Oct. 31, 2022	$ 99,000	$ 850,000	$ 1,934,000	$ (4,550,000)	$ (263,000)	$ 49,382,000	$ 47,452,000
Ending balance, shares at Oct. 31, 2022	4,100	8,502,881		3,571,963