Statements of Shareholders' Equity - USD ($)	Preferred Stock [Member]	Common Stock Class A [Member]	Paid-In Capital [Member]	Treasury Stock (Common Class A) [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]	Total
Balance at Apr. 30, 2015	$ 99,000	$ 850,000	$ 1,736,000	$ (3,558,000)	$ 1,282,000	$ 33,960,000	$ 34,369,000
Balance, shares at Apr. 30, 2015	4,100	8,502,881		3,477,156
Purchases of common stock				$ (27,000)			(27,000)
Purchases of common stock, shares				3,865
Dividend declared at $0.34 per common share outstanding						(1,709,000)	(1,709,000)
Unrealized gain (loss), net of tax effect					(935,000)		(935,000)
Net Income						3,086,000	3,086,000
Balance at Apr. 30, 2016	$ 99,000	$ 850,000	1,736,000	$ (3,585,000)	347,000	35,337,000	34,784,000
Balance, shares at Apr. 30, 2016	4,100	8,502,881		3,481,021
Purchases of common stock				$ (555,000)			(555,000)
Purchases of common stock, shares				76,585
Dividend declared at $0.34 per common share outstanding						(1,757,000)	(1,757,000)
Unrealized gain (loss), net of tax effect					892,000		892,000
Net Income						2,401,000	2,401,000
Balance at Apr. 30, 2017	$ 99,000	$ 850,000	$ 1,736,000	$ (4,140,000)	$ 1,239,000	$ 35,981,000	$ 35,765,000
Balance, shares at Apr. 30, 2017	4,100	8,502,881		3,557,606