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Stock Based Compensation - Summary of Assumptions Used in Black-Scholes Option-Pricing Model to Determine Fair Value of Stock Options (Details)
3 Months Ended
Oct. 28, 2017
Oct. 29, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Volatility, Minimum 42.10% 44.40%
Volatility, Maximum 43.50% 46.00%
Risk free interest rate, Minimum 1.90% 1.30%
Risk free interest rate, Maximum 2.00% 1.50%
Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Expected term (in years) 5 years 7 months 6 days 5 years 4 months 24 days
Maximum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Expected term (in years) 6 years 6 months 6 years 6 months