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Share-based Compensation - Option Grant Fair Value Assumptions (Detail)
9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Expected volatility 47.83% 44.99%
Expected dividends 2.63% 0.00%
Expected term (in years) 6 years 6 years
Risk-free rate 0.64% 0.70%