Consolidated Balance Sheets (Parentheticals) - USD ($) shares in Thousands, $ in Thousands	Jan. 31, 2021	Jul. 31, 2020
Trade accounts receivable (in Dollars)	$ 6,909	$ 6,085
Preferred stock par value (in Dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued
Class A common stock
Common stock, par value (in Dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	35,000	35,000
Common stock, shares issued	3,272	3,272
Common stock, shares outstanding	1,574	1,574
Treasury stock, common stock shares	1,698	1,698
Class B common stock
Common stock, par value (in Dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000	200,000
Common stock, shares issued	26,343	25,961
Common stock, shares outstanding	24,151	24,345
Treasury stock, common stock shares	2,192	1,616