Fair Value of Financial Instruments - Changes in the Level 3 Fair Value Category of Unobservable Inputs (Detail) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| State and Local Governments Tax-Exempt [Member] | ||||
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Beginning Balance | $ 185 | $ 184 | $ 185 | $ 353 |
| Change in Fair Value | $ 0 | $ 0 | $ 0 | $ 1 |
| Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent |
| Payments, Maturities & Calls | $ 0 | $ 0 | $ 0 | $ (170) |
| Ending Balance | 185 | 184 | 185 | 184 |
| State and Local Governments Taxable[Member] | ||||
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Beginning Balance | 1,264 | 1,276 | 1,270 | 1,274 |
| Change in Fair Value | $ (6) | $ (6) | $ (12) | $ (4) |
| Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent |
| Payments, Maturities & Calls | $ 0 | $ 0 | $ 0 | |
| Ending Balance | 1,258 | 1,270 | 1,258 | $ 1,270 |
| State and Local Governments [Member] | ||||
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Beginning Balance | 1,449 | 1,460 | 1,455 | 1,627 |
| Change in Fair Value | $ (6) | $ (6) | $ (12) | $ (3) |
| Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent |
| Payments, Maturities & Calls | $ 0 | $ 0 | $ 0 | $ (170) |
| Ending Balance | $ 1,443 | $ 1,454 | $ 1,443 | $ 1,454 |