Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jul. 31, 2019	Jul. 31, 2018
Allowance for doubtful accounts	$ 5,444	$ 5,358
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized shares	10,000	10,000
Preferred stock, shares issued
Common Class A [Member]
Common stock, par value	$ 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
Common Class B [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000	200,000
Common stock, shares issued	25,803	25,594
Common stock, shares outstanding	24,895	22,872
Treasury stock, common stock shares	908	2,722