Equity Incentive Plans and Benefit Plans - Employee Stock Purchase Plan Assumptions (Detail)
6 Months Ended
Jan. 31, 2015
Jan. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rates, Minimum 0.10% 0.10%
Risk-free interest rates, Maximum 0.50% 0.40%
Dividend yield 0.00% 0.00%
Volatility, Minimum 37.70% 57.20%
Volatility, Maximum 49.80% 64.40%
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 6 months 6 months
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 2 years 2 years