Net Income Per Share and Weighted Average Shares (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016
Net Income Per Share and Weighted Average Shares [Abstract]
Net income per share numerator	$ 52,727	$ 48,242	$ 101,082	$ 89,107
Net income per share denominator [Abstract]
Weighted average shares (in shares)	24,040,243	23,937,812	24,020,976	23,947,183
Add potential dilution [Abstract]
Stock options, nonvested stock awards and MSU Grants (in shares)	68,757	109,230	85,772	112,864
Diluted weighted average shares (in shares)	24,109,000	24,047,042	24,106,748	24,060,047