Staff Costs - Additional Information (Detail) |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2021
USD ($)
Employee
|
Dec. 31, 2020
USD ($)
Employee
|
Dec. 31, 2019
USD ($)
Employee
|
|
| Analysis Of Income And Expense [Abstract] | |||
| Average employed on full-time equivalents | 45.8 | 46.2 | 48.5 |
| Employed on full-time equivalents | 48.3 | 42.7 | 50.1 |
| Gain on post-employment benefits | $ | $ 864,000 | $ 0 | $ 527,000 |