Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Apr. 30, 2015	Jul. 31, 2014
Allowance for doubtful accounts	$ 5,958	$ 11,507
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized shares	10,000	10,000
Preferred stock, shares issued
Class A common stock [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
Class B common stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000	200,000
Common stock, shares issued	25,233	24,587
Common stock, shares outstanding	22,253	21,653
Treasury stock, common stock shares	2,980	2,934