Off-Balance Sheet Commitments - Allowance for Credit Losses Related to Off-Balance Sheet Items (Detail) - USD ($) $ in Thousands  | 
3 Months Ended | |
|---|---|---|
Mar. 31, 2022  | 
Mar. 31, 2021  | 
|
| Risks And Uncertainties [Abstract] | ||
| Balance at beginning of period | $ 2,586 | $ 2,792 | 
| Provision expense (recovery) for credit losses | (228) | (450) | 
| Balance at end of period | $ 2,358 | $ 2,342 | 
| X | ||||||||||
- Definition Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
  | 
| X | ||||||||||
- Definition Amount of expense (reversal of expense) for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
  | 
| X | ||||||||||
- References No definition available. 
  |