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Equity Incentive Plans - Summary Of Fair Value Of The ESPP (Detail)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend
2019 Employee Stock Purchase Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility 52.00%    
Risk-free interest rate 1.85%    
Expected term 8 months 12 days