| Off-Balance Sheet Commitments - Allowance for Credit Losses Related to Off-Balance Sheet Items (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
| Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | |
| Risks and Uncertainties [Abstract] | ||||
| Balance at beginning of period | $ 2,475 | $ 2,313 | $ 3,114 | $ 2,586 | 
| Provision expense (recovery) for credit losses | (13) | 936 | (652) | 663 | 
| Balance at end of period | $ 2,462 | $ 3,249 | $ 2,462 | $ 3,249 | 
| 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. 
 |