Retained Earnings (Schedule Of Changes In Retained Earnings) (Details) (USD $) In Thousands	3 Months Ended
	Oct. 31, 2011	Oct. 31, 2010
Retained Earnings [Abstract]
Balance as of July 31, 2011	$ 829,148
Net income	22,358	23,688
Dividends paid	(8,227)
Balance as of October 31, 2011	$ 843,279