Share-Based Payment Awards - Deferred Stock Units - Additional Information (Detail) - shares |
1 Months Ended | 9 Months Ended | |
---|---|---|---|
Jan. 31, 2019 |
Sep. 30, 2021 |
Dec. 31, 2020 |
|
2016 Long Term Incentive Plan [Member] | |||
Class Of Stock [Line Items] | |||
Ratable annual vesting period of equity awards | 4 years | ||
Non Executive Directors [Member] | |||
Class Of Stock [Line Items] | |||
Non-vested deferred stock units outstanding | 0 | 0 | |
Deferred Stock Units [Member] | |||
Class Of Stock [Line Items] | |||
Ratable annual vesting period of equity awards | 1 year | ||
Deferred Stock Units [Member] | 2016 Long Term Incentive Plan [Member] | |||
Class Of Stock [Line Items] | |||
Vested deferred stock units vested | 0 |