Consolidated Balance Sheets (Parenthetical) - USD ($)	Jul. 31, 2023	Jul. 31, 2022
Stockholders’ equity:
Convertible preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Convertible preferred stock, shares authorized (in shares)	125,000	125,000
Convertible preferred stock, shares issued (in shares)	100,000	100,000
Convertible preferred stock, accrued dividends	$ 604,000	$ 566,000
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized (in shares)	1,875,000	1,875,000
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	43,096,271	42,672,827
Treasury stock, shares (in shares)	15,033,317	15,033,317