Net Income Per Share and Weighted Average Shares (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jul. 28, 2017	Apr. 28, 2017	Jan. 27, 2017	Oct. 28, 2016	Jul. 29, 2016	Apr. 29, 2016	Jan. 29, 2016	Oct. 30, 2015	Jul. 28, 2017	Jul. 29, 2016	Jul. 31, 2015
Net Income Per Share and Weighted Average Shares [Abstract]
Net income per share numerator	$ 53,893	$ 46,924	$ 52,727	$ 48,355	$ 51,023	$ 49,169	$ 48,242	$ 40,865	$ 201,899	$ 189,299	$ 163,903
Net income per share denominator [Abstract]
Basic weighted average shares outstanding (in shares)									24,031,810	23,945,041	23,918,368
Add potential dilution [Abstract]
Stock options, nonvested stock awards and MSU Grants (in shares)									86,478	129,232	130,556
Diluted weighted average shares outstanding (in shares)									24,118,288	24,074,273	24,048,924