Summary Of Significant Accounting Policies (Calculation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Summary Of Significant Accounting Policies [Abstract]
Weighted average shares - basic									150,286,403	154,392,740	155,697,056
Diluted share equivalents									2,655,000	2,804,000	2,659,000
Weighted average shares - diluted									152,940,605	157,196,918	158,355,544
Net earnings for basic and diluted earnings per share computation	$ 70,981	$ 70,946	$ 53,821	$ 68,553	$ 65,767	$ 61,811	$ 44,579	$ 53,134	$ 264,301	$ 225,291	$ 166,163
Net earnings per share - basic	$ 0.47	$ 0.47	$ 0.36	$ 0.46	$ 0.43	$ 0.40	$ 0.29	$ 0.34	$ 1.76	$ 1.46	$ 1.07
Net earnings per share - diluted	$ 0.47	$ 0.46	$ 0.35	$ 0.45	$ 0.42	$ 0.39	$ 0.28	$ 0.34	$ 1.73	$ 1.43	$ 1.05