Consolidated Balance Sheets (Parenthetical) (USD $)	Jan. 31, 2013	Apr. 30, 2012
Statement of Financial Position [Abstract]
Allowance for doubtful accounts and sales returns	$ 200,000	$ 200,000
Common stock, par value	$ 1	$ 1
Common stock, authorized shares	9,000,000	9,000,000
Common stock, issued shares	1,755,626	1,783,885
Common stock, outstanding shares	1,755,626	1,776,568
Treasury stock (shares)		7,317