Retained Earnings (Schedule Of Change In Retained Earnings) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2012	Apr. 30, 2011
Retained Earnings [Abstract]
Balance as of July 31, 2011			$ 829,148
Net income	41,341	40,008	77,379	69,384
Dividends paid			(24,387)
Balance as of April 30, 2012	$ 882,140		$ 882,140