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Share-Based Compensation - Schedule of Grant Date Fair Values of Awards Using Monte Carlo Simulation Valuation Model (Detail)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected volatility, minimum [1] 22.00% 19.50% 20.00%
Expected volatility, maximum [1] 65.00% 21.50% 24.00%
Risk-free rate, minimum 0.30% 1.80% 2.40%
Risk-free rate, maximum 1.50% 2.40% 2.70%
Expected term   3 years 3 years
Minimum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected term 1 year    
Maximum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected term 4 years    
[1] For the years ended December 31, 2020, 2019 and 2018, the weighted average expected volatility was 46.2%, 20.5% and 24.0%, respectively.