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Equity Incentive Plans and Stock-Based Compensation (Details 3) - Employee stock purchase plan - $ / shares
9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Valuation assumptions    
Expected stock price volatility (as a percentage) 46.00% 32.00%
Risk free interest rate 0.12% 2.44%
Expected term 6 months 6 months
Weighted-average fair value of purchase rights granted under the purchase plan $ 3.50 $ 2.80