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. 30, 2015	Jan. 31, 2014	Jan. 30, 2015	Jan. 31, 2014
Net Income Per Share and Weighted Average Shares [Abstract]
Net income per share numerator	$ 47,163	$ 37,055	$ 81,187	$ 64,215
Net income per share denominator [Abstract]
Weighted average shares (in shares)	23,914,797	23,812,777	23,888,496	23,815,107
Add potential dilution [Abstract]
Stock options, nonvested stock awards and MSU Grants (in shares)	117,592	157,834	128,417	132,743
Diluted weighted average shares (in shares)	24,032,389	23,970,611	24,016,913	23,947,850