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Share-based payments - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Disclosure of terms and conditions of share-based payment arrangement [line items]      
Share-based compensation expense $ 4.4 $ 5.2 $ 7.1
Fair value of non-vested stock awards $ 91.69 $ 71.59  
Weighted average remaining contractual life 2 years 2 years 2 months 12 days  
Estimated compensation cost for next year $ 3.1 $ 3.7  
Expected term 10 years    
Bottom of range      
Disclosure of terms and conditions of share-based payment arrangement [line items]      
Vesting period 3 years    
Top of range      
Disclosure of terms and conditions of share-based payment arrangement [line items]      
Vesting period 5 years    
2024      
Disclosure of terms and conditions of share-based payment arrangement [line items]      
Estimated compensation cost for next year $ 2.2