Shareholders' Equity (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010
Acquirement minimum of outstanding common stock	15.00%
Expiration date of redeemable rights	March 2, 2016
Common stock under stock repurchase plan		8,000,000
Remaining authorization to repurchase under stock repurchase plan	5,000,000
Redeemable value per each right	$ 0.001
Series A Junior Participating Preferred Stock [Member]
Preferred stock, par value
Preferred stock, price per one one-thousandth preferred share	$ 143.00
Number of preferred stock per right unit	0.001
Fiscal 2012 [Member]
Stock repurchases	162,900
Purchase price	$ 9.2