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Stock-Based Compensation (Detail) - shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares granted (in shares) 161,000 0  
ESPP obligations      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility, minimum 30.00% 26.00% 28.00%
Expected volatility, maximum 49.00% 31.00% 49.00%
Expected term (in years) 15 days 15 days 15 days
Risk-free interest rate. minimum 2.04% 1.15% 0.40%
Risk-free interest rate, maximum 2.46% 2.22% 1.15%
Dividend yield (in percent) 0.00% 0.00% 0.00%
Common stock options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility, minimum     39.00%
Expected volatility, maximum     42.00%
Expected term (in years)     4 years 10 months 20 days
Risk-free interest rate. minimum     1.78%
Risk-free interest rate, maximum     2.47%
Dividend yield (in percent)     0.00%
Number of shares granted (in shares) 0