CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) (USD $)	Jan. 31, 2012	Apr. 30, 2011
CURRENT ASSETS:
Accounts receivable, allowance for doubtful accounts	$ 73,886	$ 146,502
Inventories, obsolete	1,075,437	1,792,681
SUPPLEMENTAL TYPE CERTIFICATES, accumulated amortization	2,518,252	2,464,183
OTHER ASSETS
Accumulated amortization other assets	451,287	292,465
STOCKHOLDERS' EQUITY:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	100,000,000	100,000,000
Common stock, issued (in shares)	57,194,262	57,194,262
Common stock, outstanding (in shares)	57,194,262	57,194,262
Common stock, owed but not issued (in shares)	278,573	278,573
Treasury stock (in shares)	600,000	600,000
Class A [Member]
STOCKHOLDERS' EQUITY:
Preferred stock, par value (in dollars per share)	$ 5	$ 5
Preferred stock, liquidation	100	100
Preferred stock, redemption value	100	100
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Class B [Member]
STOCKHOLDERS' EQUITY:
Preferred stock, par value (in dollars per share)	$ 5	$ 5
Preferred stock, liquidation	1,000	1,000
Preferred stock, redemption value	$ 1,000	$ 1,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Class A and B [Member]
STOCKHOLDERS' EQUITY:
Preferred stock, authorized (in shares)	50,000,000	50,000,000