Net Income Per Share and Weighted Average Shares (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 27, 2012	Jan. 28, 2011	Jan. 27, 2012	Jan. 28, 2011
Net Income Per Share and Weighted Average Shares [Abstract]
Net income	$ 25,609	$ 28,777	$ 49,411	$ 52,511
Net income per share denominator [Abstract]
Weighted average shares	22,968,002	23,237,493	22,919,451	23,034,943
Add potential dilution [Abstract]
Stock options and nonvested stock and stock awards (in shares)	338,175	681,758	306,512	721,624
Diluted weighted average shares outstanding (in shares)	23,306,177	23,919,251	23,225,963	23,756,567