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Share-Based Compensation - Summary of Fair Value of Stock Purchase Rights Granted under the Global Employee Stock Purchase Plan Estimated Using Weighted-Average Assumptions (Detail) - HCM Global Employee Stock Purchase Plan [Member] - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 46.40% 34.80%
Expected dividend rate 0.00% 0.00%
Risk-free interest rate 1.10% 2.20%
Expected term (in years) 3 months 18 days 4 months 24 days
Grant date fair value per share $ 17.11 $ 9.32