Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Apr. 30, 2012	Jul. 31, 2011
Allowance for doubtful accounts, trade accounts receivable (in dollars)	$ 13,493	$ 15,375
Preferred stock, par value (In dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
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	23,690	23,586
Common stock, shares outstanding	21,190	21,109
Treasury stock, common stock shares	2,500	2,477