Stock-Based Awards and Stock-Based Compensation - Additional Information (Details) - USD ($)
3 Months Ended
Apr. 30, 2017
Jan. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Unamortized stock-based compensation expense $ 6,661,000  
Stock-based compensation expense, weighted average amortization period 2 years 9 months 18 days  
Restricted Stock Units    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Stock-based compensation expense, weighted average amortization period 3 years 2 months 12 days  
Unamortized stock-based compensation expense $ 16,131,000  
2005 Stock Option Plan    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Common stock reserved for future issuance 0  
2015 Equity Incentive Plan    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Common stock reserved for future issuance 2,916,452  
Increase in common stock reserved for future issuance 1,575,956  
2015 Employee Stock Purchase Plan    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Common stock reserved for future issuance 1,297,589 857,350
Increase in common stock reserved for future issuance 630,382  
Common stock shares issued 190,143  
Share-based compensation discount from market price, purchase date 15.00%  
Share-based compensation, purchase price of common stock at fair market value percentage 85.00%  
Unamortized stock-based compensation expense $ 563,000  
Stock-based compensation expense, weighted average amortization period 1 year