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Equity Incentive Plans and Stock-Based Compensation (Details 3) - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Options      
Valuation assumptions      
Expected stock price volatility rate 38.00%    
Expected stock price volatility rate, minimum   33.00% 24.00%
Expected stock price volatility rate, maximum   36.00% 32.00%
Risk free interest rate 0.20%    
Risk free interest rate, minimum   1.40% 2.60%
Risk free interest rate, maximum   1.60% 2.80%
Expected term 5 years 6 months   5 years 9 months 18 days
Weighted-average grant-date fair value of stock options granted $ 5.46 $ 4.36 $ 4.23
Options | Minimum      
Valuation assumptions      
Expected term   5 years 1 month 6 days  
Options | Maximum      
Valuation assumptions      
Expected term   5 years 2 months 12 days  
Employee stock purchase plan      
Valuation assumptions      
Expected stock price volatility rate   32.00%  
Expected stock price volatility rate, minimum 37.00% 32.00% 27.00%
Expected stock price volatility rate, maximum 46.00% 32.00% 34.00%
Risk free interest rate 0.10%    
Risk free interest rate, minimum   1.60% 2.05%
Risk free interest rate, maximum   2.40% 2.50%
Expected term 6 months 6 months 6 months
Weighted-average fair value of purchase rights granted under the purchase plan $ 3.46 $ 3.13 $ 2.59
Stock compensation plan      
Valuation assumptions      
Dividend yield 0.00% 0.00% 0.00%