Net Earnings Per Share (Schedule Of Information Necessary To Calculate Basic And Diluted Net Earnings Per Common Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2012	Jan. 31, 2011
Net Earnings Per Share [Abstract]
Weighted average shares - basic	75,052,805	77,580,064	75,154,873	77,375,086
Common share equivalents	1,360,000	1,398,000	1,326,000	1,392,000
Weighted average shares - diluted	76,412,785	78,977,509	76,480,673	78,766,895
Net earnings for basic and diluted earnings per share computation	$ 53,821	$ 44,579	$ 122,374	$ 97,713
Net earnings per share - basic	$ 0.72	$ 0.57	$ 1.63	$ 1.26
Net earnings per share - diluted	$ 0.70	$ 0.56	$ 1.60	$ 1.24