v3.20.1
Stock-Based Compensation - Fair Value of Options (Details)
12 Months Ended
Jan. 31, 2020
Jan. 31, 2019
Jan. 31, 2018
Employee Stock Purchase Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield 0.00%    
Employee Stock Purchase Plan | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years) 6 months    
Risk-free interest rate 1.60%    
Expected stock price volatility 30.10%    
Employee Stock Purchase Plan | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years) 2 years    
Risk-free interest rate 2.20%    
Expected stock price volatility 35.70%    
Shares of common stock issuable from stock options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years) 6 years 18 days   6 years 18 days
Dividend yield 0.00% 0.00% 0.00%
Shares of common stock issuable from stock options | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years)   6 years 18 days  
Risk-free interest rate 2.00% 2.60% 1.90%
Expected stock price volatility 37.70% 37.80% 40.30%
Shares of common stock issuable from stock options | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years)   7 years 6 months 7 days  
Risk-free interest rate 2.40% 3.10% 2.20%
Expected stock price volatility 37.90% 38.90% 41.40%